Device and method for subgingival measurement

ABSTRACT

A method for measuring regions of a tooth in a mouth including: measuring at least one surface point on a surface of the tooth with respect to an element mechanically coupled to said surface point; determining a location of at least one visible reference mechanically coupled to said surface point with respect to said element; estimating a location of said surface point with respect to said visible reference. A device used for such measuring may include a main body comprising a final optical element of an imager which defines an optical field of view directed in a first direction; and a measurement element coupled to said main body extending generally in said first direction; where a tip of said measurement element is sized and shaped to be inserted between a tooth and adjacent gingiva; where said optical field of view is sized to image at least part of a tooth.

RELATED APPLICATION/S

This application claims the benefit of priority under 35 USC §119(e) ofU.S. Provisional Patent Application No. 61/745,744 filed Dec. 24, 2012,the contents of which are incorporated herein by reference in theirentirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to dentalmeasurements, and more particularly, but not exclusively, to a deviceand method for subgingival measurement.

Dental treatments often involve measurement of the patient's mouth. Inparticular, construction of crowns, bridges and other dental prostheticsgenerally involves measurement or acquisition of three dimensionalmodel/s of existing dental structures. Often prosthetics extend belowthe gum line, and measurement of dental structures below the gum line iscarried out. Accurate measurement/s and/or modeling can facilitate agood fit of the prosthetic constructed using the measurements/s and/ormodel/s to the patient's mouth.

Dental impressions are a traditional technique for providing a model ofthe mouth. Generally, a cast is produced from the impression and thecast then is used to produce the prosthetic. Such techniques suffer frominaccuracy due to multiple manual steps which can be technicallydemanding on the dentist as well as invasive and uncomfortable for thepatient, especially if subgingival measurement is necessary.

More recently, digital scanning techniques have offered increasedaccuracy and detail of measurement. However, such techniques are onlyable to image, measure and model visible parts of the patient's mouthand generally do not provide imaging of subgingival areas. CT scanningcan provide measurement of subgingival areas, however it does notprovide soft tissue measurement.

Both existing physical impression methods and digital impression methodsof measurement of subgingival areas usually include the step ofphysically separating the gingiva from the circumference of the tooth(or teeth) to be measured for the time that measurements are taken. Thisseparation usually causes bleeding which needs to be stemmed orprevented before measurements can be made. The process of separationsometimes causes trauma to the gingiva, which can lead to inflammationand permanent damage to the gingiva.

One common technique for separating gingiva from the teeth forsubgingival measurements is cord packing, where cord/s are insertedbetween the tooth/teeth and gingiva, holding the gingiva away from thetooth surface. Cord packing is generally a time consuming procedure,stressful and technically demanding for the dental practitioner andpainful for the patient.

Dental practitioners may have a dilemma, either to use damaging,painful, technically challenging methods to expose subgingival toothareas (e.g., cord packing) for measurement or to forgo subgingivalmeasurements resulting in either ill-fitting prosthetics or prostheticswith unpleasing aesthetics where the border between the prosthetic andoriginal tooth structure is visible above the gum line.

Additional background art includes U.S. Pat. No. 7,346,417, U.S. Pat.No. 5,257,184, U.S. Pat. No. 5,320,462, U.S. Pat. No. 7,625,335, U.S.Patent Application Publication No. US2008261165, U.S. Pat. No.7,813,591, FR2692773, U.S. Pat. No. 5,224,049, U.S. Pat. No. 5,372,502,U.S. Pat. No. 7,494,338.

SUMMARY OF THE INVENTION

There is provided in accordance with an exemplary embodiment of theinvention, a method for measuring regions of a tooth in a mouthcomprising:

measuring at least one surface point on a surface of the tooth withrespect to an element mechanically coupled to said surface point;

determining a location of at least one visible reference mechanicallycoupled to said surface point with respect to said element;

estimating a location of said surface point with respect to said visiblereference.

In an exemplary embodiment of the invention, measuring comprisesmeasuring at least one surface point on a subgingival surface of thetooth. Optionally or alternatively, determining comprises:

capturing at least one image of said visible reference using an imager;and

determining said location of said visible reference uses said at leastone image.

Optionally, the method comprises calibrating said imager using a knowndimension of said visual reference. Optionally or alternatively, saidmeasuring comprises measuring using a stylus, a tip of which contactssaid location. Optionally, the method comprises detecting a contact ofsaid tip with said location. Optionally or alternatively, measuringcomprises measuring while scanning said tip along a surface of saidtooth. Optionally, scanning comprises:

vibrating said stylus in a generally coronal-apical direction whilstkeeping in contact with a tooth surface.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said determining comprises detecting a non-axialdeflection of said stylus. Optionally or alternatively, said determiningcomprises determining a stylus tip location. Optionally, saiddetermining a stylus tip location comprises analyzing an image smear insaid image.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said element is part of a probe body including animager final optical element; and

measuring is measuring with respect to said body.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said element comprises a stylus or part thereof;and measuring is measuring with respect to said stylus.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said visible reference comprises a visible toothportion.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said visible reference comprises at least onemarker.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said visible reference comprises a stylus or aportion thereof.

In an exemplary embodiment of the invention according to any of theprevious embodiments, generating a measurement tooth model using saidestimated location. Optionally, generating comprises:

registering said visible reference with an existing tooth model;

extending said existing tooth model with said location of said surfacepoint to create said measurement tooth model. Optionally, saidregistering comprises registering an image acquired for said determiningto said model. Optionally or alternatively, said registering comprisesregistering using a marker on the tooth. Optionally or alternatively,said registering comprises generating a 3D model and registering said 3Dmodel to said existing tooth model. Optionally, said generating a 3Dmodel comprises generating a point cloud and registering said pointcloud to said existing tooth model.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said determining uses an imager and wherein saidgenerating comprises generating a tooth model using images acquired withsaid imager.

In an exemplary embodiment of the invention according to any of theprevious embodiments, the method comprises generating a tooth model fromsaid estimating and combining said generated tooth model with adifferent tooth model.

In an exemplary embodiment of the invention according to any of theprevious embodiments, the method comprises repeating said measuring,determining and estimating for a plurality of locations of surfacepoints. Optionally, the method comprises generating a sub-gingival modelfrom said plurality of estimated locations. Optionally or alternatively,the method comprises illuminating said tooth during said determining.

In an exemplary embodiment of the invention according to any of theprevious embodiments, the method comprises also estimating at least onelocation not on said tooth.

In an exemplary embodiment of the invention according to any of theprevious embodiments, the method comprises associating, by a computer, atype information with said location, responsive to one or both of userindication or prompt by a computer system prior to said measuring.

There is provided in accordance with an exemplary embodiment of theinvention, a device for measuring regions of a tooth comprising:

a main body comprising a final optical element of an imager whichdefines an optical field of view directed in a first direction; and

an elongate measurement element coupled to said main body and extendinggenerally in said first direction;

wherein a tip of said measurement element is sized and shaped to beinserted between a tooth and adjacent gingiva;

wherein said a distance between said tip and said body is small enoughso that said device can fit inside an adult human mouth and

wherein said optical field of view is sized to image at least part atooth when such tooth is contacted by said tip.

In an exemplary embodiment of the invention, said tip is formed of orcovered with a material softer than tooth dentin. Optionally oralternatively, said elongate measurement element is in the form of astylus. Optionally or alternatively, said stylus is flexible. Optionallyor alternatively, the device comprises at least one sensor which sensescontact of said tip with said tooth. Optionally or alternatively, thedevice comprises at least one sensor which detects a deflection of saidelongate element.

Optionally or alternatively, the device comprises at least one sensorwhich detects a movement of said tip.

In an exemplary embodiment of the invention, said sensor is located at acoupling between said measuring element and said body. Optionally oralternatively, said sensor is located at or adjacent said tip.

In an exemplary embodiment of the invention, the device comprises anactuator which moves said tip in a scanning pattern. Optionally, saidscanning pattern comprises a vertical scanning.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said optical field of view comprises at least twooverlapping fields of view.

In an exemplary embodiment of the invention according to any of theprevious embodiments, the device comprises said imager.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said final optical element comprises a mirror.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said elongate measurement element comprises atleast one marking or light source positioned in said field of view.

In an exemplary embodiment of the invention according to any of theprevious embodiments, the device comprises at least one illuminationelement which illuminates said tooth and said measurement element.

In an exemplary embodiment of the invention according to any of theprevious embodiments, the device comprises a cover on which saidelongate measurement element is mounted.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said tip is thicker than a thickness of saidelongate measurement element adjacent said tip.

In an exemplary embodiment of the invention according to any of theprevious embodiments, said tip is rounded.

In an exemplary embodiment of the invention according to any of theprevious embodiments, the device comprises circuitry for estimating alocation of said tip based on an image acquired via said imager.

In an exemplary embodiment of the invention, said circuitry estimates amovement of said tip relative to said body based on an image acquiredvia said imager. Optionally or alternatively, the device comprisescircuitry for generating a surface of said tooth, including at least onesub-gingival surface portion using said estimated location. Optionallyor alternatively, the device comprises circuitry for interpreting acontacting of said tip as an input to mark a tooth model with additionalinformation.

There is provided in accordance with an exemplary embodiment of theinvention, a device comprising a connector and an extending elongatemeasurement element with a tip adapted to be placed between a gingivaand a tooth, said device sized to fit in a human mouth, the connectorhaving an inner geometry configured to mount on an intra-oral scanner.Optionally, said connector comprises a cover with a sealed window forsaid imager.

There is provided in accordance with an exemplary embodiment of theinvention, an attachment sized for intraoral use and configured forrigid attachment to a handheld probe, comprising a mirror and anelongate measurement element, wherein said mirror defines an opticalfield of view directed in a first direction and wherein said elongatemeasurement element extends into said field of view and has a tipadapted to be placed between a gingiva and a tooth.

There is provided in accordance with an exemplary embodiment of theinvention, a system comprising:

an imager;

an elongate measurement element with a tip adapted to be placed betweena gingiva and a tooth; and

circuitry configured to analyze an image acquired by said imager andreconstruct a location of said tip when said tip is invisible betweensaid gingiva and said tooth.

There is provided in accordance with an exemplary embodiment of theinvention, an intraoral scanner sized for intraoral use for scanning atooth, comprising:

at least one light source;

at least one imager; and

circuitry configured to reconstruct a shape of a tooth from imagesacquired by said imager using light from said light source,

wherein said circuitry is operative to recognize a tool used to retracta gingiva as not being part of said tooth. In an exemplary embodiment ofthe invention, said circuitry identifies said tool based on its movingbetween different images. Optionally or alternatively, said circuitryidentifies image portion near a tip of said tool as portions to beconsidered when building a sub-gingival portion of said reconstruction.

There is provided in accordance with an exemplary embodiment of theinvention, a method of intra-oral scanning of at least one tooth,comprising:

identifying, during scanning, the retraction of a gingiva by a tool; and

reconstructing a model of a tooth while not incorporating an image ofsaid tool into the model and incorporated a portion of said toothexposed by said retraction.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

Implementation of the method and/or system of embodiments of theinvention can involve performing or completing selected tasks manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of embodiments of the method and/or systemof the invention, several selected tasks could be implemented byhardware, by software or by firmware or by a combination thereof usingan operating system.

For example, hardware for performing selected tasks according toembodiments of the invention could be implemented as a chip or acircuit. As software, selected tasks according to embodiments of theinvention could be implemented as a plurality of software instructionsbeing executed by a computer using any suitable operating system.

In an exemplary embodiment of the invention, one or more tasks accordingto exemplary embodiments of method and/or system as described herein areperformed by a data processor, such as a computing platform forexecuting a plurality of instructions.

Optionally, the data processor includes a volatile memory for storinginstructions and/or data and/or a non-volatile storage, for example, amagnetic hard-disk and/or removable media, for storing instructionsand/or data. Optionally, a network connection is provided as well. Adisplay and/or a user input device such as a keyboard or mouse areoptionally provided as well.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced. In some caseselements in corresponding figures have corresponding numbers, which arenot necessarily explicitly described.

In the drawings:

FIG. 1A is a is schematic drawing of an original tooth;

FIG. 1B is a schematic drawing of a prepared tooth;

FIG. 1C is a schematic drawing of a crowned tooth;

FIG. 2A is a schematic drawing of an embodiment of a device formeasuring subgingival tooth portions in accordance with an/someexemplary embodiment/s of the invention;

FIG. 2B is a flow chart of a method of extending a tooth model by onesubgingival point in accordance with an/some exemplary embodiment/s ofthe invention;

FIG. 2C is a flow chart of a method in accordance with an/some exemplaryembodiment/s of the invention;

FIG. 2D is a schematic drawing of a stylus path with respect to a topview of teeth in a jaw in accordance with an/some exemplary embodiment/sof the invention;

FIG. 3A is a schematic drawing of a top view of an embodiment of adevice for measuring subgingival tooth portions with four cameras inaccordance with an/some exemplary embodiment/s of the invention;

FIG. 3B is a side view of an embodiment of a device for measuringsubgingival tooth portions with four cameras in accordance with an/someexemplary embodiment/s of the invention;

FIG. 4A and FIG. 4B are top views of an embodiment with two camerasmeasuring a tooth in accordance with an/some exemplary embodiment/s ofthe invention;

FIG. 5A and FIG. 5B are top views of an embodiment with two cameras anda flattened cross section stylus measuring a tooth in accordance withan/some exemplary embodiment/s of the invention;

FIG. 6A and FIG. 6B are top views of an embodiment with four camerasmeasuring a tooth in accordance with an/some exemplary embodiment/s ofthe invention;

FIG. 7 is a schematic diagram of an embodiment with a spherical stylustip in accordance with an/some exemplary embodiment/s of the invention;

FIG. 8 is a schematic diagram of an embodiment including a sensor inaccordance with an/some exemplary embodiment/s of the invention;

FIG. 9A is a schematic diagram of an embodiment with a sensor at thestylus tip in accordance with an/some exemplary embodiment/s of theinvention;

FIG. 9B is a schematic diagram of an embodiment with a mechanism foroptical verification of contact between the stylus and subgingivalpreparation margin in accordance with an/some exemplary embodiment/s ofthe invention;

FIG. 10 is a schematic diagram of an embodiment where stylus movement isoptically tracked in accordance with an/some exemplary embodiment/s ofthe invention;

FIG. 11 is a schematic diagram of an embodiment with a side attachedstylus in accordance with an/some exemplary embodiment/s of theinvention;

FIG. 12 is a schematic diagram of an embodiment of a system forproducing a dental prosthetic in accordance with an/some exemplaryembodiment/s of the invention;

FIG. 13 is a flow chart that illustrates an exemplary method forcreation of tailored dental prosthetics in accordance with an/someexemplary embodiment/s of the invention;

FIG. 14 is a flow chart which shows a method and algorithm for creatinga 3D model of a tooth in accordance with an/some exemplary embodiment/sof the invention;

FIG. 15 is a flow chart which shows a method and algorithm for alignmentin accordance with an/some exemplary embodiment/s of the invention;

FIG. 16 is a schematic diagram of an embodiment with a side attachedangled stylus in accordance with an/some exemplary embodiment/s of theinvention;

FIG. 17 is a schematic diagram of an adaptor which side attaches to animager in accordance with an/some exemplary embodiment/s of theinvention;

FIG. 18 is a schematic diagram of an adaptor which covers a part of animager including a mirror in accordance with an/some exemplaryembodiment/s of the invention

FIG. 19 is a schematic diagram of an adaptor including a sensor inaccordance with an/some exemplary embodiment/s of the invention;

FIG. 20 is a schematic diagram of an embodiment where the stylus andimager are separate parts in accordance with an/some exemplaryembodiment/s of the invention; and

FIG. 21 is a schematic flow chart of a full calibration procedure, inaccordance with an exemplary embodiment of the invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to dentalmeasurements, and more particularly, but not exclusively, to a deviceand method for subgingival measurement.

Overview

An aspect of some embodiments of the invention relates to measuringregions of a tooth, especially subgingival portions, for example, usingcontact measurement. In some embodiments a stylus tip is put intocontact with a subgingival surface of a tooth. The subgingival surfaceof the tooth is then measured by estimating a location of the stylus tipwith respect to a visible reference of a visible portion of the tooth(e.g., tooth portion surface topography, marker on the tooth, stylus)giving a stylus tip location. In some embodiments measurement is usingimages/s collected by an imager. In some embodiments the stylus isattached to the imager. In some embodiments the imager and the stylusare separate components.

The term ‘stylus’, as used in this document, refers to any elongatedmeasurement element (EMD) with an elongated measurement element tip(stylus tip) sized and shaped to be inserted between a tooth andadjacent gingiva. In some embodiments a body of the elongatedmeasurement element (stylus) is relatively uniform. In some embodimentsthe body of the elongated measurement device (stylus) is non-uniform inshape and/or dimension, e.g., conical, forked. In some embodiments theelongated measurement device includes a neck adjacent to the EMD tipwhich is of different dimension and/or shape than the EMD tip and/or EMDbody e.g., the EMD neck is narrower than the EMD tip and EMD body.

In some embodiments, multiple measurements of different subgingivalsurfaces are combined to generate a surface topography model of at leasta subgingival area of the tooth.

In some embodiments, measuring includes repeating measurement fordifferent subgingival surfaces: In some embodiments the stylus tip isput into contact with a subgingival surface of a tooth and the stylustip location is estimated, the stylus tip is then put into contact witha different surface of a tooth and the a stylus tip location isestimated again. In some embodiments, repeating measurement fordifferent subgingival surfaces is manual, where the user places thestylus tip into contact with different subgingival surfaces or moves(scans) the stylus tip along the tooth surface. In some embodiments,measurement for different subgingival surfaces (e.g., stylus scanning)is automatic, for example where one or more actuators move the stylusand/or a main body to which the stylus in some embodiments is attached(in some embodiments, main body includes the imager). In someembodiments, the stylus moves, for example, vibrates, automaticallyperforms vertical (coronal-apical) movements and the user manually movesthe stylus around the tooth. In some embodiments, the stylusautomatically performs complex movements e.g., horizontal vibration,combined vertical and horizontal movements, combined vertical movementsand/or movements perpendicular to tooth surface.

In some embodiments stylus location and/or stylus tip location e.g., ismeasured.

In some embodiments, stylus tip location is measured/by mechanicalmeasurements, for example stylus deflection, stylus e.g., applied forcemagnitude and/or direction for example using one or more force sensor(e.g., load cell, strain gauge) In some embodiments one or more forcesensor is located at a stylus connection to the main body and/or along astylus length and/or at the stylus tip.

In some embodiments, stylus and/or stylus tip location is measuredoptically, for example by measuring a location of one or more stylusmarking.

In some embodiments, stylus and/or stylus tip location ismeasured/tracked magnetically and/or using linear encoder/s and/or usingproximity sensor/s.

In some embodiments, stylus location and/or stylus tip location ismeasured repetitively during stylus movement (e.g., during stylusscanning) In some embodiments a stylus movement is measured. Repetitivestylus location and/or stylus tip measurements and measuring a stylusand/or stylus tip movement are referred to by the term ‘tracking’. Insome embodiments optical tracking of the stylus and/or one or morestylus marking is by measuring an image smear.

In some embodiments, two or more stylus measurements are combined togenerate a measured tooth model. In some embodiments, one or more stylusmeasurement is combined with a supragingival tooth model measuredseparately (e.g., from digital imaging, CT scan, MRI scan, 3D intraoralscanner, 3D scan of convention impression). In some embodiments one ormore stylus measurement is combined with a supragingival tooth modelextending the model. In some embodiments, a subgingival tooth model iscombined with a supragingival tooth model.

In some embodiments, combining a two or more tooth measurements is byaligning of two or more images. In some embodiments aligning two or moreimages is by matching of 3D image information. In some embodimentsaligning two or more images is by pattern matching of 2D features and/ornatural marks on a tooth surface. In some embodiments aligning two ormore images is by matching one or more marker placed on a portion of themouth being measured (e.g. placed on a coronal portion of the preparedtooth).

In some embodiments, two or more tooth models (e.g., a model generatedfrom stylus measurements and a model generated by another measurementdevice e.g. CT, MRI, optical scanner) are combined. In some embodimentscombining two or more models is by matching of 3D topographyinformation. In some embodiments combining two or more models is bypattern matching of 2D features and/or natural marks on a tooth surface.In some embodiments combining two or more models is by matching one ormore marker placed on a portion of the mouth being measured (e.g. placedon a coronal portion of the prepared tooth).

In some embodiments, a tip of the stylus (stylus tip) is thin enough(e.g., a stylus thickness is less than 1 mm) to be easily insertedbetween a tooth surface and gingiva causing a reduced level of damage tothe gingiva than the damage caused to the gingiva by cord packing orretraction paste, for example half the level of damage. In someembodiments, the stylus has varying cross-sectional area along thestylus length for example, for example so that the stylus preferentiallybends at one or more point, so that the stylus is more rigid at one ormore point.

In some embodiments, a vertical dimension of stylus and main body can beheld inside a human adult mouth.

In some embodiments, one or more imaging parameters are selected and/orset for imaging mouth structures and the stylus when the stylus is inposition in contact with a tooth to be measured. In some embodiments,one or more imaging parameters are selected to provide clear enoughimages from which measurements (e.g. 3D topography and/or marker ortooth feature location, stylus location) are determined, for exampleresolution, modulation transfer function (MTF), imaging wavelength/s. Insome embodiments, parameters are selected so that at least a regionadjacent to the stylus tip is imaged, for example field of view (FOV),depth of field (DOF), focal length. In some embodiments, one or moreimaging parameter are selected at manufacture of the device. In someembodiments, one or more imaging parameter are selected duringcalibration after manufacture or before collecting measurements. In someembodiments, one or more imaging parameter are selected duringmeasurements (e.g. focus, FOV, DOF, focal length).

In some embodiments, an illumination level of the mouth features to bemeasured and/or of the stylus is selected for measurements, for example,in some embodiments, high illumination levels and/or pulsed illuminationfor optical tracking of rapid stylus movements.

In some embodiments, patterned light (e.g. a grid) is projected onto oneor more mouth structure and mouth structure 3D topography is estimatedfrom images using the imaged patterned light as is known in the art ofestimating 3D topography using patterned light.

In some embodiments, contact of the stylus tip to the tooth is verifiedin order to verify that collected measurements are of the tooth surface.In some embodiments, if contact of the stylus to the tooth portion isnot verified, a user is informed (e.g. by alarm and/or message presentedon a user interface). In some embodiments, during stylus measurements,contact of the stylus tip to the tooth is verified by a stylus parameter(e.g., stylus parameter is within a range or above or below a threshold)selected from applied force magnitude, applied force direction, stylusdeflection, subgingival surface expected depth.

Optionally, the device is part of a system for producing dentalprosthetics. The system can include a processing application operativeto do one or more of; generate a tooth model from measurements andoptional preexisting tooth model and/or generate a prosthetic modeland/or to send the prosthetic model to a machine for construction of theprosthetic.

In some embodiments, the imager includes one or more camera. In someembodiments, the imager includes more than one camera to provide depthinformation. In some embodiments, the imager includes more than onecamera for image around and obstruction (e.g., by the stylus). In someembodiments, the imager includes an image sensor (e.g., CMOS sensor, CCD(Charge Coupled Device) sensor). In some embodiments, the imagerincludes a plenoptic camera. In some embodiments, the imager includes animage sensor with more than one optical aperture e.g., a single CMOScamera with four lenses that produce four images over four quadrants ofthe CMOS sensor. In some embodiments, additional camera/s provide imagesof other teeth and/or other mouth areas. Some embodiments includeadditional camera/s which can optionally have a wide field of view. Insome embodiments, additional camera/s provide jaw information forprosthetic design (e.g., neighboring teeth topography and/or oppositejaw tooth/teeth topography with respect to the prepared tooth is in someembodiments, used to guide prosthetic dimensions) and/or improveorientation accuracy of the imager in relation to tooth for imagematching.

An aspect of some embodiments of the invention relates to using gingivalretraction with existing intraoral scanners. In an exemplary embodimentof the invention, the oral scanner is programmed to identify and ignoreor remove the form of a tool used for gingival retraction, form theimage. Optionally, the tool includes a marking or color to assist suchrecognition. Optionally or alternatively, the shape of the tool sirprovided to the intraoral scanner. Optionally, the shape of parts of thetooth that are exposed by the retractor are used to build a tooth model,and may comprise a sub-gingival portion thereof. Optionally, theselocations are automatically identified based on their color and/or basedon them being near the tip of the retraction tool.

Optionally or alternatively, a tool as described herein is used to scanmechanically such sub-gingival regions, while the intra-oral scanner isoperating.

In an exemplary embodiment of the invention, the gingival retraction isprovided using a stylus or other elongate measurement element whichmounts to the intraoral scanner. Optionally, the intraoral scanner isprogrammed to ignore blockage of some of its field of view by such anelement. Optionally, the connection of the element to the intraoralscanner is rigid.

In this and other embodiments, the tip of the measurement element isoptionally rounded, for example, to reduce gingival damage. Optionallyor alternatively, the tip includes a stop (e.g., a shelf extending awayfrom the element, which stop interferes with over insertion of the toolunder the gingiva. Optionally or alternatively, the tip is made flexibleenough so that it bends if used to retract the gingiva too strongly.Optionally or alternatively, the stylus body is made flexible enough sothat it bends (e.g., enough to slide past tooth) under a relatively lowforce, for example, at a force selected in the range between 1 and 500grams, for example, between 1 and 100 grams.

In this and in other embodiments it is noted that circuitry whichperforms calculations such as image registration and tooth modelgeneration, may be provided at a remote location. For example, raw imageand/or sensor, may be sent remotely and a generated model and/orlocation position sent back. Optionally, a remote server which providessuch functionality associates the model and/or data with a particularpatient, tooth, intra-oral scanner (e.g., type and/or code and/or styluscode) and/or practitioner.

An aspect of some embodiments of the invention relates to disposablemeasurement elements. In some embodiments, a sterile cover with anextending elongate measurement element is used and is designed to mounton an existing or a novel intra-oral scanner. In another embodiment aconnector rather than a cover is used. In some embodiments, only thestylus is disposable. In another embodiment, the body of the intraoralscanner is disposable, but with respect to imaging elements, these areprovided in a probe to which the body is attached, and the bodyoptionally includes an optical element such as a mirror to shape thedesired imaging field.

In some embodiments, the imager is a separate component not connected tothe stylus. In some embodiments the imager is not connected to thestylus and is an existing intraoral scanner and the stylus, duringscanning, for example, moves one or more portion of the gingiva awayfrom the tooth and/or provides a visible reference.

In some embodiments, the user moves the stylus within the patient'smouth and the stylus movement is measured. Optionally, user stylusmovements within the mouth can be combined with a tooth model, forexample the user can manually move the stylus over a tooth preparationfinish line (user-inputted finish line) and the line is combined with atooth model. Optionally, the user-inputted finish line is displayed onthe tooth model to the user through a user interface.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings. The invention is capable of otherembodiments or of being practiced or carried out in various ways.

In this document directions and orientations are given using standarddental directions (e.g., coronal, apical, buccal, lingual) and/or aregiven with respect to the orientation of the figures (e.g., vertical,horizontal, above, below).

Crowning a Tooth

Referring now to the drawings, FIG. 1A, FIG. 1B and FIG. 1C illustratethe process of crowning a tooth in preparation for using methods anddevices in accordance with some embodiments of the invention. FIG. 1A isschematic drawing of an original tooth 100 and surrounding gingiva (orgums) 102. FIG. 1B is a schematic drawing the tooth of FIG. 1A afterpreparation (e.g., for a crown or a bridge). FIG. 1B shows preparedtooth 104 (also termed tooth peg), gingiva 102, and subgingivalpreparation area 106. As can be seen, only a supragingival tooth portionthe coronal side of (or above) a gum line 107 is visually exposed fordigital impression, standard impression or other tooth measurementswithout performing invasive procedures to reveal the subgingivalregions, e.g., cord packing. A preparation finish line 108 delineatesthe border between a prepared tooth portion in the coronal direction(above) and a natural tooth portion in the apical direction (below)Preparation finish line 108 separates between the natural tooth whichincludes the tooth enamel coating and the prepared tooth from which theenamel has generally been removed. A subgingival preparation area is thetooth area apical of (below) gum line 107 and coronal of (above)preparation finish line 108 and includes a subgingival preparationmargin. Generally, the subgingival preparation margin has a step likeshape (the step shape can be rounded). The step like shape is around atleast a portion of the tooth where subgingival preparation finish line108 is the outer edge of the step.

Generally, a well-fitting crown or bridge covers all portions of thetooth which have been shaped or prepared (e.g., by drilling), the toothportions above or coronal of preparation finish line 108. In someembodiments, for construction of a prosthetic which fits the preparedtooth well, measurements of tooth subgingival area is accurate to about200μ or about 100 μm or about 40 μm or about 30 μm or about 10 μm orintermediate or better accuracies. A reason for covering all preparedareas of the tooth with the crown is as, during preparation, toothenamel is often removed leaving any uncovered portions vulnerable todecay.

FIG. 1C is a schematic drawing of a crowned tooth and illustrates acrown 112 which has been affixed (usually glued) over prepared tooth104. Gingiva 102 meet the crown at a crown gum line 114. Typically,crown 112 restores the general shape of the original tooth. FIG. 1Cillustrates a well-fitting crown with a smooth subgingival join/junctionbetween the crown at subgingival preparation finish line 108 which, inthis case, is also a finish line of the crown. A smooth surface junctionbetween the prosthetic and the natural tooth is often desirable as anycracks or crevices can provide a hospitable environment for bacteria.Bacteria can cause gum inflammation resulting in tooth decay and/or boneresorption and even tooth loss. Subgingival placement of the preparationfinish line and/or the prosthetic finish line is for example, foraesthetic reasons (color difference or visible junction between thenatural tooth and a prosthetic) and/or for covering preexistingrestorations (e.g. fillings) which extend beneath the gum line.

Generally, it is desirable that an inclination (slope, gradient) of thecrown surface at the crown finish line will be the same as theinclination of the natural tooth surface adjacent to the crown finishline in the apical direction to provide a smooth or gentleincline/gradient over the crown finish line. In some embodiments, (e.g.,in order to match the crown/prosthetic inclination with the naturaltooth inclination) the 3D surface dimensions of the tooth portion aboveline 110, where line 110 is approximately 0.5 mm-1 mm or approximately0.1 mm-5 mm beyond (in the apical direction of) subgingival preparationarea 108 is measured.

Exemplary Subgingival Measurement Device

FIG. 2A is a schematic drawing of a side view of an embodiment of adevice for measuring subgingival tooth portions 216 which is also termeda Subgingival Margin Probe (SGMP), in accordance with some exemplaryembodiments of the invention. As shown, SGMP 216 includes a stylus 218(or other elongate measurement element) and a main body 220. In theillustrated embodiment main body 220 optionally houses an imager and theimager optionally includes cameras 230 and 232. In an exemplaryembodiment of the invention, the imager has a field of view which canimage stylus 218, an area of a tip thereof and/or an area of the toothagainst which the stylus is placed. Optionally, the imager is used tocapture information about the tooth which can be used to register and/orgenerate to a tooth model, and/or is used to collect information aboutthe stylus. In FIG. 2A, SGMP 216 is illustrated in position formeasuring subgingival tooth portions where a stylus tip 222 at a distalend of stylus 218 has been inserted between gingiva 202 and preparedtooth 204.

In some embodiments, tooth measurement is by inserting stylus 218 inbetween ginviva 202 and prepared tooth 204. In some embodiments, theimager (e.g. cameras 230 and 232) is used to measure a stylus tipposition, for example, directly (stylus tip visible to imager) and/orindirectly (stylus tip invisible to imager). In some embodiments thestylus tip position is estimated from images with respect to a visibletooth portion. In some embodiments the imager includes two cameras 230and 232 which provide images of the same 3D feature from which depthinformation is extracted. In some embodiments the images are matched(possibly at a later time) to a model of the tooth, so that the relativeposition of the stylus tip and the tooth can be ascertained therefrom.

In some embodiments, rigid attachment of stylus to main body and rigidstylus 218 mean that the stylus end location with respect to the mainbody is known and maintained during scanning. In some embodiments, astylus proximal side 224 is attached to main body 220. In someembodiments, attachment of stylus proximal side 224 to main body 220 isrigid. In some embodiments, stylus 218 is rigid.

In some embodiments, attachment of stylus proximal side 224 to main body220 is rigid but stylus 218 is flexible allowing stylus tip 222 to movewith respect to main body 220. In some embodiments, attachment of stylusproximal side 224 to main body 220 is flexible allowing stylus 218 tomove with respect to main body 220. In an exemplary embodiment of theinvention, movement of the stylus is used for one or both of identifyingcontact of the stylus with a tooth (e.g., if the tooth deflects thestylus) or to allow scanning motion of the stylus and estimation of atip location based on movement of the stylus relative to body 220.

In some embodiments, as illustrated in FIG. 2A, the imager is located inmain body 220. The example schematically shown in FIG. 2A includes twocameras 230 and 232. In some embodiments, the imager (e.g., cameras 230and 232) captures images of tooth 204 from different directions and maybe used to image the 3D contour of tooth 204 and/or optionally the 3Dcontour of gingiva 202, gum line 207 on tooth. In some embodiments,reconstruction of 3D features (e.g., visible tooth surface) from imagesuses, for example Moire topography methods (fringe pattern modeling),stereoscopy or other methods known in the art of oral or non-oral 3Dscanning or shape reconstruction from images.

Optionally, main body 220 includes one or more illumination elements forexample light/s (e.g., LED, standard bulb) and/or pattern projector/s.Optionally, the illumination elements are used for 3D shapereconstruction (e.g., by projecting patterned light). Optionally oralternatively, the element(s) are used for providing light for theimager and/or dentist and/or to illuminate the stylus.

In some embodiments, during measurement with the SGMP, stylus 218 liftsgingival tissue 202 revealing a portion of subgingival area 206,optionally including preparation finish line 208, temporarily to cameras230, 232. The revealed portion of subgingival area 206 can then bemeasured using image/s collected by cameras 230, 232 optionallyincluding stylus 218 and/or stylus marking/s 234.

Methods

FIG. 2B is a flow chart of a method of extending a tooth model by onesubgingival point in accordance with an/some exemplary embodiment/s ofthe invention.

At 201, a visible tooth portion is modeled. In some embodiments,modeling of the visible tooth portion is by processing images collectedby the imager and/or by scanning the visible tooth portion with thestylus. In some embodiments, modeling of the visible tooth portion usesintraoral digital scanning. In some embodiments, modeling of the visibletooth portion uses standard impression without separation of the gumsfrom the teeth followed by 3D scanning of the impression or impressioncast. In some embodiments, modeling of the visible tooth portion isusing CT, MRI or X-ray images. At 203, a location of one subgingivalpoint on the surface of the tooth with respect to the visible toothportion is then determined.

At 205, the model is then extended using the location of the subgingivalpoint. In some embodiments, this method is repeated for multiplesubgingival points in order to provide a 3D tooth model includingsubgingival areas. In some embodiment the 3D tooth model is a surfacetopography model.

In some embodiments, for example, if the model to be extended is asupra-gingival model (e.g., acquired with the SGMP) and/or is a modelbuilt up using locations, the extending may be carried out after thefact. For example, raw images and/or sensor measurements are collectedand sent to a processor which then generates a model and/or extends amodel and/or combines two models. Optionally, a low quality model may bequickly reconstructed, for example, to support basic Q/A by the dentist.

When extending the model, extending may be of a point or more at a time,or, for example, a model is built up using the points and that model ismerged with an existing model (e.g., using smoothing where there isoverlap).

FIG. 2C shows a method of determining a location of a point on asubgingival tooth surface with respect to a visible tooth portion.

At 207, a stylus is put into position in contact with a point on asubgingival (or non-visible) tooth surface.

At 209, an image of a visible tooth portion is collected. Optionally,the image of the tooth portion provides information as to the toothportion dimension/location with respect to the imager.

At 211, the stylus tip location with respect to the imager (or otherfixed point) is optionally determined. In some embodiments, this is afixed distance due to the stylus being rigid. In other embodiments, thestylus is moved and/or may move or deflect and sensor measurements whichcapture this information may be used to correct the determination. Insome embodiments, act 211 is not carried out as such, rather thecalculation of stylus tip position relative to the tooth maymathematically incorporate this determination without actuallyperforming it explicitly.

At 213, the stylus tip location (and/or location of contacted toothsurface) with respect to the visible tooth portion is optionallydetermined from the tooth portion dimension/s with respect to the imagerand the stylus tip location with respect to the imager.

In some embodiments, marker/s are affixed to the tooth or another mouthstructure. In some embodiments, determining a location of a point on asubgingival tooth surface is with respect to such a marker, for example,as follows:

(i) An image of a marker is collected.

(ii) The image and/or other detection of the marker provides informationas to the marker location with respect to the imager.

(iii) The stylus tip location with respect to the imager is optionallydetermined (e.g., 211).

(iv) The stylus tip location with respect to the marker is optionallydetermined from the marker location with respect to the imager and thestylus tip location with respect to the imager.

In some embodiments, the location of marker/s in relation to the visibletooth portion is known (e.g., by a processing circuitry, for example,based on user entry, contacting a marker with the stylus tip and/or codeentry, which code is associated with such information) and the stylustip location with respect to the visible tooth portion is determinedfrom the stylus tip location relative to the marker/s, for example,using analytical geometry methods.

In general, it is noted that item positions in this and otherembodiments may be extracted from images using various methods,including such as known in the field of image processing. Variousgeometric calculation methods may be used, for example, as known in 3Dgeometrical processing. Model/image matching and/or reconstruction mayuse method known in the art of image matching and 3D and/or surfacemodel matching.

In some embodiments, the location of marker/s in relation to the visibletooth portion is determined by measuring, using the stylus tip andimages, a set of locations on the visible tooth portion, and integratingor matching (e.g., using cloud-of-points matching techniques) the set ofmeasured locations in relation to the visible tooth portion model tofind the marker/s location and subgingival point in relation to thevisible tooth portion model.

Scanning

In some embodiments, multiple subgingival measurements according to themethods described in this document are made (e.g., as described in FIG.2B and FIG. 2C). In some embodiments, multiple measurements fordifferent subgingival surfaces are manual, where the user places thestylus tip into contact with different subgingival surfaces or moves thestylus tip along the tooth surface (scans) manually.

In an exemplary embodiment of the invention, by providing multiplemeasurements a shape of a surface of the tooth can be reconstructed. Inan exemplary embodiment of the invention, the surface to bereconstructed is between 10% and 100%, for example, between 20% and 70%of the sub-gingival (and above bone) surface of the tooth, for example,up to 1 mm, 2 mm, 3 mm, 5 mm or intermediate or greater depth below thegum line and/or below a step formed in the tooth for crowning.Optionally, the scanned area is between 10% and 100% (e.g., between 20%and 70%) of the circumference of the tooth. In some cases surfaces ofmore than one tooth are reconstructed. Optionally or alternatively,scanning also includes supra-gingival parts of the tooth. In someembodiments, scanning is repeated, for example, a dentist modifying thetooth shape after reviewing a model (or other visualization) generatedfrom the tooth data.

Some of the methods described herein provide faster acquisition and/orincreased accuracy while measuring, for example, by incorporatingsubstantially continuous measurement of tip location (which may beuseful even for manual scanning) and/or data acquisition at a ratefaster than image acquisition.

In some embodiments, scanning is where the stylus tip is movedcoronal-apically (approximately vertically) whilst remaining in contactwith the tooth surface (similar to the scraping movements generallyemployed by dentists when cleaning plaque from a tooth or whenconducting a pocket survey.) as illustrated by arrows 226 and 228 inFIG. 2A. Although referred to in this document as coronal/apicalmovement, vertical movement, up/down movement, as the stylus remains incontact with the surface of the tooth the movement may also include anon-coronal/apical movement component of the stylus tip. In someembodiments, as described in more detail below, scanning is bycoronal/apical movements of the main body, and/or of the stylus proximalend but, due to stylus deflection and/or deformation, the stylus tipperforms the coronal/apical whilst remaining in contact with the toothsurface movement as described above. In some embodiments, for the stylusto remain in contact with the tooth, the stylus is contacted to thetooth with a lateral force in the direction of the tooth surface. Insome embodiments, lateral force is provided by elasticity of the stylusattachment to the main body, and/or stylus elasticity. In someembodiments, lateral force is provided by application (e.g., by anactuator) of a shift manually or automatically of the stylus and/or mainbody towards the tooth center.

In some tooth preparations, the prepared tooth includes sharp anglese.g., a step shape at the tooth preparation finish line (the junctionbetween prepared tooth and natural tooth). If the prepared toothincludes a step shape vertical stylus scanning in the coronal-apicaldirection whilst staying in contact with the tooth surface may bedifficult to perform. This may be due to the high angle between the stepshape and the natural tooth (e.g., the stylus gets caught by highangles, the stylus looses contact and jumps across high angles).

In some embodiments, difficulties in vertical stylus scanning can beovercome by scanning perpendicular to the tooth surface. In someembodiments, stylus scanning movements, which are automatic in someembodiments, are vertical movements over some tooth surface andmovements perpendicular to the tooth surface over some tooth surfaces(e.g. the stylus scans an upper portion of a tooth step shape verticallyand a base section of a tooth step shape perpendicular to a toothsurface. In some embodiments, stylus scanning movements, which areautomatic in some embodiments are combined vertical movements andmovements perpendicular to the tooth surface or along tooth surface(e.g., helical movements in space or circular movements relative totooth surface).

FIG. 2D is a schematic drawing of a top view of teeth in a jaw. Preparedtooth or tooth peg 204 is shown in context with other teeth in a jaw221. A stylus first position 218 a, a stylus second position 218 b and astylus path 219 show a stylus scanning movement around prepared tooth204. In some embodiments, scanning movement is clockwise along path 219around prepared tooth 204. In some embodiment scanning movement isanticlockwise along path 219 around prepared tooth 204. In someembodiments, scanning movement is continuous along path 219 aroundprepared tooth 204. In some embodiments, scanning movement isnon-continuous along path 219 around prepared tooth 204.

In some embodiments, scanning of the subgingival margin is by repetitivestylus movements in one general direction whilst moving the stylus inanother general direction. For example, the coronal-apical stylusmovement whilst remaining in contact with the tooth surface, asdescribed above, in some embodiments, is combined with stylus movementaround stylus path 219 (e.g. the stylus vibrates vertically while it isscanned around the tooth).

In some embodiments, the coronal/apical movement whilst remaining incontact with the tooth surface is achieved by the stylus tip moving withrespect to the main body while the stylus movement around path 219 is byboth the stylus and the main body. In some embodiments, the stylus moveswith respect to the main body for both coronal/apical movements whilstin contact with the tooth surface and stylus movement around path 219.In some embodiments, main body 220 is fixed to the prepared tooth,and/or another tooth, and/or teeth, and/or or the jaw and/or to anexternal fixture and/or by the patient biting down on one or moreportion of the device.

In some embodiments, scanning is by successive stylus movements aroundthe prepared tooth (e.g., around path 219) at different depths(coronal-apical positions) on the tooth.

In some embodiments, stylus scanning of the tooth can be automaticwhere, for example, motor/s (e.g., actuator/s) move the stylus and/orthe stylus body. In some embodiments, the device can scan the toothpartially automatically e.g., where coronal/apical whilst in contactwith the tooth surface movements as described above are automatic andthe user manually moves the stylus around path 219.

Surrounding mouth structures to prepared tooth 204 include, for exampleteeth, palate, tongue, cheeks, gingiva. The surrounding mouth structuresdiffer at stylus positions 218 a and 218 b: At 218 a the stylus is notadjacent to other teeth, but is adjacent to the tongue. At 218 b thestylus is adjacent to adjacent tooth 344. In some positions around path219 surrounding mouth structures can form obstructions to imaging.

In an exemplary embodiment of the invention, vertical scanning isprovided by a coupling between the stylus and the body, which couplingincludes a length changing element, such as a linear actuator or apiezoelectric element. Similar structures and/or structures such asdescribed below, may be used to provide stylus movement.

In an exemplary embodiment of the invention, during signal processing ofacquired signals, data relating to when the stylus tip is in contactwith the tooth is saved, while other data is optionally discarded and/ornot used for imager reconstruction.

In an exemplary embodiment of the invention, image acquisition continuesduring scanning, optionally, the rate of image acquisition and/or timingthereof, being matched to scanning parameters.

While scanning is described herein to collect information to construct atooth model, in some embodiments, scanning or single contact is used fordata entry. In one example, a user can “mark” on a tooth by indicatingsuch to a user interface and then contracting the tooth and or scanningalong a portion thereof. Due to the earlier indication, this informationmay be stored, optionally together with a reconstructed or other toothmodel, as (also) indicating something other than a mere surface. Oneexample, is marking of a finishing line. Another example, is a markingof a boundary where sub-gingival scanning is needed.

Exemplary Shape and Dimensions

In some embodiments, a stylus tip thickness is between 0.1 mm and 2 mmor between 0.5 mm and 1.5 mm potentially preventing insertion of stylus218 from damaging the patient's gingiva, and assisting the user(dentist) in inserting and moving the stylus during measurements. If thestylus tip has a circular cross section the stylus tip thickness is thestylus diameter. If the stylus tip has a non-circular cross section thestylus tip thickness is the smallest distance between two points on thecircumference of the cross-section which can be connected by a straightline through a center point of the cross-section. In some embodiments,the stylus tip thickness is smaller than 1 mm. In some embodiments,stylus 218 has a varying thickness along the stylus length between0.05-7 mm, or between 0.5-3 mm. In some embodiments a varying stylusthickness along the stylus length (e.g., stylus tip has a smallerthickness than the stylus thickness at the stylus attachment to the mainbody) enables the stylus to deflect without collapsing.

In some embodiments stylus is shaped that the tip is cone shaped with astylus body having approximately the same diameter as the circular baseof the cone shaped tip (e.g., stylus shape is similar to a pencilshape).

A thin stylus (e.g., where the stylus body excluding stylus tip is lessthan 3 mm in diameter or less than 1 mm diameter) can be flexible,deflecting when force is applied during scanning. In some embodiments,attachment of the stylus to the main body is not fully rigid resultingin mechanical tolerances in the connection of the stylus the main body.In some embodiments, stylus flexibility and mechanical tolerances ofstylus-main body connection allow the stylus tip to move 10-100 μmrelative to the main body during scanning (due to forces applied forstylus insertion and scanning movements). In some embodiments the stylustip can have larger movements relative to main body for example, thestylus tip moves up to 2 mm with respect to the main body. In someembodiments, as are described in more detail below, a stylus tiplocation relative to the main body is estimated.

In some embodiment SGMP main body 220 is held by the dentist whenscanning the tooth. In some embodiments, a vertical part of SGMPincluding the stylus and at least a portion of the main body which isconnected to the stylus can be put into a patient's mouth e.g., a height978 illustrated in FIG. 9A. In some embodiments, a height or verticaldimension of SGMP, from the stylus tip to a top of main body (e.g.,height 978 illustrated in FIG. 9A) is less than 10 cm or less than 7 cmor less than 5 cm or less than 3 cm. As described previously, in someembodiments, measurements are taken when stylus is inserted in anapical-coronal (vertical) orientation. In some embodiments, a styluslength is less than 8 cm, or less than 5 cm or less than 3 cm, or lessthan 2 cm. In some embodiments, a final optical element, e.g., camera/s,mirror, is within 8 cm or within 4 cm or within 2 cm of the stylus tip.

Subgingival Device Including Four Cameras

In some embodiments, multiple cameras, (e.g., four cameras) collectimages of adjacent teeth. For example, in FIG. 3B, adjacent tooth 344,is seen by cameras 332 and 342. In some embodiments, images of adjacentteeth are used to obtain measurement or models which include adjacentteeth. In some embodiments, measurement or models which include adjacentteeth are used to determine the boundaries of a crown, bridge or otherprosthetic. In some embodiments, images of adjacent teeth are used inregistration of collected images with a tooth model (e.g., tooth modelfrom intraoral scanner, scanning standard impression, CT).

Referring now to FIG. 3A and FIG. 3B. FIG. 3A illustrates a top view ofan embodiment where a main body 320 includes four cameras 330, 332, 340and 342. Also visible is a main body cable 348. In some embodiments,main body is elongated and in some embodiments, main body hangs out ofthe patient's mouth during measurement. An elongated main body isillustrated by break 349.

FIG. 3B illustrates a side view SGMP including the main body of FIG. 3A.Also illustrated in FIG. 3B are stylus 318, stylus markings 334, tooth304, gingiva 302, adjacent teeth 344 and 346, cable 348, break 349. FIG.3B illustrates stylus 318 in between prepared tooth 304 and adjacenttooth 344, similar to stylus second position 218 b illustrated in FIG.2D.

In some measurement stylus positions (e.g., around path 219 in FIG. 2D)surrounding mouth structures can form obstructions to imaging.Increasing the number of SGMP cameras means that if a camera's view isobstructed, another camera or cameras may have an unobstructed view. Forexample, at least a portion of the subgingival margin region 350, shownin FIG. 3B, can be seen by two cameras 330 and 340.

In some embodiments, four cameras image stylus 318 and stylus markings334 and the stylus tip location is estimated at a high accuracy (e.g.,accurate to within 10 μm) relative to tooth 304.

FIG. 3A and FIG. 3B also schematically show cable 348 that can connectmain body 320 with an external power supply and/or a processingapplication (e.g., processing application 1280). In some embodiments,(including the embodiment illustrated by FIG. 2A.) SGMP 216 is wireless,with, for example, an internal battery for power supply. In someembodiments, wireless SGMP 216 includes a wireless communicationinfrastructure e.g., for communication with an external processor orprocessing application.

In some embodiments, during measurements with the stylus, as illustratedin FIG. 3B, the stylus is orientated in the coronal-apical directionwhere a tilt angle θ to a distal-mesal direction (horizontal) a isapproximately 90°. In some embodiments, the stylus is orientated atapproximately 90° to a buccal-lingual direction (not illustrated).However, in some embodiments, measurements can be collected where thestylus is inserted at a different angle, for example where tilt angle tothe distal-mesal direction and/or to the buccal-lingual direction isless than 90°, or less than 45° or less than 20°. In some embodiments,the stylus is tilted for tooth measurement below the preparation finishline or for tooth measurement of tooth surfaces where the angle of thetooth to the apical-coronal direction increases (e.g., the tooth narrowstowards the tooth root). Whilst travelling around path 219 the styluscan move through different angles or orientations. For example, in someembodiments, an angle at which the stylus is inserted at first stylusposition 218 a and an angle at which the stylus is inserted at secondstylus position 218 b are different. In some embodiments, a gap betweenthe prepared tooth and an adjacent tooth is smaller than the stylus tipdiameter and the stylus is inserted for measurement of subgingivalsurfaces from the side (e.g., from a buccal or lingual direction) at ahigh tilt angle (e.g., at a tilt angle to the buccal-lingual directionof less than 45°). In some embodiments, an angle of a stylus portionorientation adjacent to main body (as illustrated in FIG. 3B by angle β)with respect to main body is 90°, or angled and between 45° and 90°, orangled below 45°.

Imaging and Cameras

FIG. 4A, FIG. 4B, FIG. 5A, FIG. 5B, FIG. 6A and FIG. 6B are top views ofembodiments showing cameras' field of view (FOV) for three exemplaryembodiments of the device. Illustrated top views are of a cross sectionof the cameras FOV above the tooth, (and a stylus cross section) ascameras FOV and overlap varies with depth: In some embodiments camerasthree dimensional shape is a truncated cone shape, the truncated tip ofthe FOV at the camera lens.

FIG. 4A and FIG. 4B show a top view of a tooth 404 being measured by anembodiment with two cameras. Also illustrated are cameras' FOVs 430, 432for the two cameras and a stylus 434 (for clarity the main body is notillustrated). In FIG. 4A both cameras view tooth 404 and the stylus.FIG. 4B illustrates the device of FIG. 4A where the device has beenmoved around the tooth, but without rotating the main body and/orcameras. In FIG. 4B stylus 434 and tooth 404 somewhat obstruct the viewof the cameras. In some embodiments, the overlapping FOV of the camerasis set to be at the tooth and stylus.

FIG. 5A and FIG. 5B illustrate an embodiment with a stylus which has aflattened cross section. A flattened stylus cross section means that asthe stylus is moved around the tooth it tends to rotate: In FIG. 5B thecameras' FOV 530, 532 and stylus 543 have rotated with stylus 534 asstylus 534 has been moved around tooth 504 and FOV 530, 532 of thecameras remains unobstructed. In some embodiments, as illustrated inFIG. 5A and FIG. 5B the cameras rotate as the stylus is moved (orscanned) around the tooth. In some embodiments, the stylus,imager/cameras and main body rotate as the stylus is scanned around thetooth. In some embodiments the imager is rotated (e.g. the camera FOVmovement as illustrated in FIG. 5A and FIG. 5B) without rotating otherparts of the main body during stylus scanning around the tooth. Apotential advantage of the imager rotating while one or more part of themain body does not rotate is that the main body can have one or moredimension which can not fit into a human mouth, (e.g., cable 348). Forexample, in some embodiments, the stylus and imager/cameras are mountedto the main body through a rotating head which can be rotatedautomatically or manually during the stylus scan around the tooth.

FIG. 6A and FIG. 6B illustrate an embodiment similar to that illustratedin FIG. 3A and FIG. 3B with four cameras. FIG. 6A and FIG. 6B show tooth604, stylus 618 and cameras' FOV 630, 632, 640, 642. FIG. 6B shows that,when stylus 618 is moved around the tooth, at least two cameras have anunobstructed view.

Optionally, structured light can be projected onto the visible toothportion/s and/or visible mouth portion/s in order to improve theaccuracy of estimations of surface topography (e.g., of supragingivaltooth portion surface topography) from collected images. In someembodiments, the SGMP includes one or more pattern projector forilluminating structured light. In some embodiments, patterns known inthe art of 3D shape reconstruction using structured light are used. Insome embodiments, patterns with spatial coding and/or wavelength codingand/or temporal coding (alternating structured patterns) as are known inthe art of pattern projection are used. In some embodiments, astructured light projector is located on main body (e.g., 855 on FIG.8). Alternatively, in some embodiments, a structured light projector islocated on a separate unit from stylus and main body. A potentialbenefit of using structured light is that 3D depth information can becollected with one camera.

In some embodiments, the device includes cameras in addition to camerasin main body which are external to the main body and stylus. Forexample, a separate unit with an imager can be temporarily attached ontoa tooth adjacent (e.g., tooth 344 or tooth 346 on FIG. 3B.) to the toothto receive a crown or other prosthetic, whilst collecting measurementswith SGMP (e.g., stylus scanning, collecting images). In someembodiments, the separate imager unit tracks stylus 318 and/or collectsimages of the tooth being measured and/or other mouth structures. Insome embodiments, a structured light projector is located on an externalcameras module/unit.

In some embodiments, an imager or cameras unit can be located at anopposite side of the jaw to the tooth being measured providing a sideview of the tooth being measured and the stylus.

In some embodiments, a portion or portions of a main body and/or animager unit can have a thickness such that the patient who is having atooth measured can hold it in position by biting down on a portion ofthe imager or cameras unit. In some embodiments, an imager or camerasunit is used to keep the patient's mouth open during measurements. Insome embodiments, an imager or cameras unit is held on an externalfixture.

Optionally, in some embodiments, the main body does not include animager/cameras, and the imager (e.g., cameras) are located on anexternal unit or units. In some embodiments an imager external unit orunits are affixed to the patient's teeth and/or jaw and/or are hand heldby a user. FIG. 20 is a schematic diagram of an embodiment where thestylus and imager are separate parts: A stylus 2018 is attached to amain body 2020. In some embodiments, main body 2020 is elongated asillustrated by a break 2049. An imager 2030 which includes a window 2058is not attached to stylus 2019 or main body 2020. In some embodimentsimager 2030, is a commercially (e.g., supra-gingival) availableintraoral scanner, but the software of such scanner is modified, forexample to support sub-gingival imaging and/or ignore the stylus duringreconstruction, for example, as described below. As illustrated by FIG.20, in some embodiments, stylus 2018 contacts tooth 2004 at a stylustilt angle 200 to the horizontal 20 a, which is not 90° (e.g., asillustrated, tilt angle 200 is less than 90°). A potential advantage ofa camera-free main body is that is that stylus can have a very thin andlightweight handle (main body), as is common with dental tools e.g.,dental probes. In some embodiments, a camera-free main body and stylusare disposable.

Optical measurement using high magnification cameras can be challengingas the Depth Of Field (DOF) or the range of depths for which the camerais in good focus may be relatively small (such as in microscopes).Depending on the lens numerical aperture of a camera, the camera DOF canbe e.g. below 0.1 mm. Some existing intraoral scanners which do not usefocus scanning (e.g., 3M ESPE Lava™ Chairside Oral Scanner), to collectmeasurements guide the user to in holding the scanner at the correctdistance, through a user interface, for focus.

In embodiments where the stylus is attached to the imager, the distancebetween the stylus tip and the imager is mechanically stabilized meaninga range of focus distances of camera/s are set (e.g. at devicemanufacture and/or by the user before and/or during scanning). In someembodiments the range of focus distances (distances where imagescollected by camera are in focus) of the camera are set to cover aregion of space at the stylus tip (e.g., at device manufacture). In someembodiments the rage of focus distances of the camera are set to coveran estimated region of space which includes the subgingival marginand/or visible tooth portion/s when the stylus is in contact with asubgingival tooth potion. A potential benefit of mechanically settingthe distance between camera/s and/or final optical element/s is that theuser is not involved with focusing the device or holding the device atthe correct distance from the tooth to be measured for focusing. Anotherpotential benefit of mechanically setting the distance between camera/sand/or final optical element/s is that focusing is more accurate andrapid making scanning faster and/or more accurate than existing dentalscanners.

In some embodiments, measurements can be taken by collecting severalimages for each camera position at different focus distances (e.g.,scanning lens focus), for example by moving the camera lens. In thisembodiment scanning lens focus is combined with mechanical stabilizationof the distance between the camera/s and the areas to be imaged, wheremechanical stabilization is by stylus mechanical coupling to the imagerfinal optical element. A potential benefit of scanning lens focuscombined with mechanical stabilization of the focus distance to theregion of interest in the tooth is that the number of focus distancesteps (and/or required range of focal lengths) for a particular imagesharpness (e.g. over the whole tooth) may be reduced. One manner ofreduction (e.g., and speedup and/or accuracy improvement) is that imagesfor focus distance steps to compensate for an unknown distance betweencamera and the region of interest in the tooth are not collected.

Some embodiments include one or more camera with a wider field of viewwhich is used to collect additional images of the prepared tooth, and/orother teeth and/or mouth structure/s. In some embodiments, registeringimages of prepared tooth with wider field of view images are used toorientate the main body and/or in registration of measurements with awhole tooth model or teeth model.

In some embodiments, images including the tooth being measured andadditional mouth structures (e.g., one or more image collected by one ormore wider field of view camera) are matched with one or more image ofthe prepared tooth from the imager. This provides an orientation tocollected images of the prepared tooth within the mouth assistingmatching of prepared tooth images and/or measurements.

In some embodiments, a wider field of view camera is attached to themain body. In some embodiments, a wider field of view camera is attachedto a mouth structure, or is held in position outside the mouth. In someembodiments, a camera with a wider field of view is used to collectimages for construction of a coarse 3D model of neighboring teeth to thetooth being measured and/or of the whole jaw.

Optionally, the main body includes one or more additional camera/s wherethe camera/s are pointing in the opposite direction, for exampleadditional camera/s are pointing approximately 180° from the directionof cameras collecting images of the prepared tooth (field of view isinverted). In some embodiments, camera/s pointing in the oppositedirection collect of images of the opposite jaw to the tooth beingmeasured. In some embodiments, images of the tooth or teeth opposite toa planned prosthetic (e.g., crown, bridge) in the opposite jaw are usedto provide a prosthetic which fits the tooth/teeth in the opposite jawgiving the prosthetic a good bite or closure with opposite teeth.

In some embodiments, the additional cameras FOV is located further fromthe prepared tooth than FOV/s of the imager, so that the location ofadditional camera/s may be less restricted than that of the imager(e.g., additional cameras can be placed in a SGMP handle). This mayassist in maintaining a form factor and/or size suitable for intraoraluse.

In some embodiments, the imager includes one or more mirrors withdifferent angles which provide two or more fields of view to one camera.This may reduce the number of imaging sensors while allowing images frommultiple points of views to be acquired.

In some embodiments, image processing (e.g., by processing application1280 described below) of images (e.g., of marker, and/or stylus and/orstylus markings and/or visible tooth portion) can use subpixelresolution or super resolution providing resolution of 1/10 of a pixelor more. In some embodiments, multiple interactions between a feature(e.g., marker, marking, tooth features) and pixels are used. In someembodiments, multiple images are used. For example, images can bealigned with each other and/or a model and/or markings can be measuredwith a sub-pixel accuracy using techniques that take advantage of thefact that an image feature (such as a tooth surface feature or marker)to be matched/measured intersects multiple pixels.

In some embodiments, imaging is during movement or vibration of one ormore part of the SGMP. In some embodiments, one or more deviceparameters, such as a main body mass, a main body mass relative to astylus mass and/or a main body mass relative to lateral movement springforces, are selected so that movement or vibration of the stylus has areduced or a known effect (e.g., by causing image smear). In someembodiments, a main body mass is high relative to a stylus mass and/orto lateral movement spring forces, reducing vibration of main body 820during stylus 818 movement. In some embodiments, main body mass is morethan 10 g or more than 20 g or more than 50 g or more than 100 g or morethan 500 g. In some embodiments, ratio of a main body mass to a stylusmass is more than 2:1 or more than 5:1 or more than 10:1 or more than50:1 or more than 100:1 or more than 1000:1.

In some embodiments, optionally or alternatively movement of the imagerdue to stylus vibration or movement is compensated. In some embodiments,movement of the imager is compensated by using image stabilizationtechniques as known in the art e.g., by synchronizing a movement of oneor more imager lens and/or imager final optical element to the stylusmovement. In one embodiment an imager lens moves with oscillations ofthe same frequency as vertical stylus scanning movements. Optionally oralternatively, a sensor, such as an accelerometer or gyroscopic sensorcoupled to the main body, can also be used for detecting the scanningmotions or vibrations and predicting them so that synchronizationbetween movement, image processing and/or image acquisition, can beprovided.

In some embodiments, an imager includes an imaging sensor and otheroptical elements (e.g., lenses), which together define an opticalpathway which defines a field of view in the mouth. Optionally, one ormore imager part is at a separate location from other imager part/s. Theimager part with the shortest direct visible optical path to the stylustip is herein termed ‘imager final optical element’ or ‘final opticalelement’ (e.g. a path folding mirror or lens or transparent solidoptical port). In some embodiments, ‘camera/s’ are described and it isto be understood that, in these cases the words ‘camera’, ‘cameras’ and‘camera/s’ are to be understood as equivalent to the word ‘imager’.

In some embodiments, the stylus tip location is measured (e.g., by forcesensor) at a higher rate than the camera/s collect images.

In some embodiments, the stylus tip location is calibrated to a toothmodel coordinates system and the stylus tip location is measured at ahigher rate than imaging.

Stylus Markings and Self-Calibration

Optionally, as illustrated in FIG. 2A (and FIG. 3B), stylus 218 includesone or more markings 234 (and 334) along the stylus. In some embodimentscameras 230 and 232 optically track stylus 218 by taking images ofstylus 218, including markings 234 along its body. Using stylus markings234 the location of stylus body 218 and accordingly the location ofstylus tip 222 relative to tooth 204 can be estimated from the imagestaken by said cameras even when stylus tip 222 is not visible to thecamera.

In some embodiments, as illustrated in FIG. 2A and FIG. 3, stylusmarkings are contrast color markings on the stylus. In some embodimentsstylus marking/s can be mirror/s. In some embodiments stylus marking/scan be high contrast markers e.g. retroreflector, specular sphere,planar mirror, spherical shaped mirror. In some embodiments one or morestylus marking is self illuminating, (e.g. LED), optionally one or moreself illuminating marking is powered by one or more wire which runthrough a hollow stylus connecting LED/s to a power source (e.g.battery). In some embodiments the stylus is hollow, illuminated fromwithin (e.g., using an internal fiber optic and/or a light sourceattached at a base of the stylus), and marking/s are window/s or beamshaping elements in the stylus.

Optionally, stylus marking/s can be used for SGMP self-calibration ofthe imager: Known stylus dimensions and/or marker dimensions and/ordistance between marker/s and/or displacement along the stylus ofmarker/s can be used to calibrate the imager where images of knowndistances/dimensions provide a scale to the imager. In one example, animage of the stylus including markings is acquired and the position ofthe markings on the image extracted. A comparison of the extractedpositions to known positions can be used to determine calibrationsettings. A potential benefit of SGMP self-calibration is if theimager/camera/s suffer a mechanical shock (e.g. the device is dropped)or undergo thermal changes. Mechanical shock/s or thermal changes toSGMP can cause elements within the imager (e.g. cameras, camera lenses)to move meaning that any previous calibration (e.g. factory calibration)is no longer accurate.

In some embodiments the SGMP can self-calibrate the stylus tip locationwith respect to the imager (e.g. calibrate stylus length). In someembodiments SGMP stylus tip self-calibration is by imaging the stylustip and stylus marking/s together and estimating the stylus tip 3Dlocation in relation to the stylus body and stylus marking/s from thecollected images.

In some embodiments the SGMP can self-calibrate the stylus tip locationwith respect to the imager using a tooth model (tooth coordinatessystem). The stylus tip 3D location in relation to the tooth coordinatessystem is estimated from collected images of the stylus and/or stylusmarking/s and visible tooth portion or tooth marker/s. The SGMP imageror main body location with respect to the tooth coordinates system isestimated from images of tooth (or tooth marker/s). The stylus tip 3Dlocation relative to SGMP main body is then estimated.

In some embodiments self-calibration is performed before startingmeasurements, e.g., in the clinical setting, outside of the patient'smouth. In some embodiments, (e.g. stylus tip self-calibration) isconducted following replacement of a part (e.g. replacement of adisposable part).

In an exemplary embodiment of the invention, calibration is used toadjust (and optionally match) the calibration settings of two cameras(e.g., if so provided). After calibration, the two cameras shouldestimate the location of a same marking (or the tip) to be the same.

In some embodiments at least some calibration is performed in thefactory and/or after usage, for example, periodically or for a new batchof disposable components and/or per use. Different calibration levelsand/or parameters may be performed at different times.

The calibration can include one or both of both imager camera “intra”parameters (e.g., focal length, center offset, lens distortion, CMOSpixels scaling and/or skew factors) and “inter” camera parameters (e.g.,relative position, orientation, rotation and/or offset), the latter casebeing sometimes useful for stereophotogrammetry configurations whetherpassive or active. “inter” parameters relating camera position and/ororientation to SGMP body and/or stylus may be of interest (instead or inaddition). In an exemplary embodiment of the invention, matching ofpoints upon the stylus surface and/or given background/calibrationtarget/projected pattern, whether in single or in multiple camerasimages, together with the a-priori marking proportions reference is usedfor calibration parameters extraction and correction.

One example is a standard checkerboard pattern with given square sizeupon a plane: The distinguishable squares' cross points are detected andcompared between the reference and resultant image. The reference imagecan be a theoretical pattern in case of a single camera calibration oran image acquired by a different camera. The deviation between theresultant grid vs. the reference one is then optionally formulated intoa calibration parameters equation system and solved for parameterextraction.

Due to the perspective nature of the 3D into 2D camera projection (e.g.,size vs. distance ambiguity), such a solution may miss one scalingparameter in the general case (e.g., occasional matching points and notspecific calibration target) and a reference object of a known size maybe used for a full calibration—the relative size of the object in theimage plane with respect to its known size, reveals the missing scalingfactor. Optionally, the markers upon the SGMP (e.g., stylus) are used tofulfill requirements for a full calibration.

FIG. 21 is a schematic flow chart of a full calibration procedure, inaccordance with an exemplary embodiment of the invention, which may beimplemented for example, on a computer or other circuitry.

At 1900, first match points are located in the series of images/imagepair/calibration target.

At 1902, various methods, for example, an 8 point algorithm in case of astereo pair, may be used for system calibration up to scaling.

At 1904, optionally in parallel, the stylus is segmented out from theimage 1904. Optionally, at 1906, markings of the stylus are detected.

At 1908, the relative markings locations in the calibrated up to scalesystem are optionally scaled 1908, for example, using a proportionsdatabase 1910.

At 1912, the resultant calibration parameters are optionally updated for3D model calculation.

Stylus Tracking

In some embodiments, the stylus can move during scanning of a tooth.Such motion may be, for example, intentional (e.g., due to vibration)and/or unintentional (e.g., due to deflection of the stylus due to forceexerted on it by a tooth). Optionally, the stylus tip 3D location istracked with respect to the imager or main body e.g. tracking themovement of the stylus during scanning. In some embodiments, thelocation of the stylus markers is tracked, which can then be processedto yield a position of the tip.

In some embodiments tracking comprises optical tracking of visibleportion/s of the stylus and/or stylus marking/s, optionally using imagescollected by imager. In some embodiments optical tracking isalternatively or additionally using an optical position sensor, e.g.position sensitive diode (PSD). In some embodiments optical tracking isby measurement of a direction of a beam reflected from the stylus orstylus marking/s.

In some embodiments images (frames) are collected by the imagerdetermining the position of the stylus and/or stylus markings in eachframe. In some embodiments the imager collects images at a frameduration and/or a frame rate is timed for capture stylus movements, suchthat the path of the stylus and/or stylus marking/s at each frame isseen as smeared image. Smeared stylus and/or marker/s images can be usedto estimate the 3D path of stylus relative to main body during eachframe period. For example, in some embodiments, the start and end of animage smear are used to calculate a stylus and/or marking/s starting anda finishing position respectively, the length of an image smear and/orthe frame rate is used to estimate a stylus and/or markings speed ofmovement.

In some embodiments, the effect of stylus movement (e.g. vibration) onimage smear measurements is reduced, and/or an image smear created bystylus movement is reduced by collecting images at a high sample rateand/or high shutter speed (e.g. 1 μsec), and/or increasing illumination(e.g., increased illumination facilitates high shutter speed). In someembodiments, the illuminator pulses and/or is synchronized with imagerimage capture (e.g. shutter speed and rate) In some embodiments, pulsingthe illuminator saves power and/or reduces heat created by theilluminator.

Optionally, the location of stylus tip (e.g. relative to the main body)is tracked by using magnetic tracking where magnet/s or electromagnet/s(DC or AC modulated) are mounted to the stylus. For example, in someembodiments, one or more magnet and/or one or more electromagnet isattached to the stylus and one or more magnetic sensor is attached tothe main body. In some embodiments magnetic tracking is of a scanning orvibrating (e.g. vertical scanning) stylus tip.

Optionally, the location of the stylus tip (e.g. relative to the mainbody) is tracked by mounting at least one mirror to the stylus,illuminating the stylus with collimated light and measuring a reflectedbeam direction with a Position Sensitive Diode (PSD) to measure stylusdeflection. In some embodiments a PSD is attached to the main body.

Optionally, the location of the stylus tip (e.g. relative to the mainbody) is tracked using one or more proximity sensor e.g. capacitiveproximity sensor, optical proximity sensor. Optionally, the stylusposition is estimated using one or more linear encoder/s e.g. capacitiveencoder, optical encoder. Optionally, the stylus position can beestimated using one or more LVDT (linear variable differentialtransformer) sensor. In some embodiments proximity sensor/s and/orlinear encoder/s and/or LVDT sensor/s provide stylus tip location towithin 10 μm at a 10 kHz sampling (measurement) rate.

Optionally, the location of the stylus, and in particular of a vibratingstylus relative to scanner main body is tracked optically using twocameras. In some embodiments tracking is with a global shuttersynchronized to stylus movements (e.g. vibrations) which captures thevibrating stylus smeared image. In some embodiments, a global shutter issynchronized to stylus vibrations by driving vibrations and camera usingthe same circuit and/or by adapting acquisition time to match thevibrations. In some embodiments, the stylus smear in captured imagetypically depends on the ratio between stylus vibration period andcamera integration time. In some embodiments stylus vibration has anon-constant speed and the image smear depends on phase of the stylusvibration. In some embodiments the imager includes global shuttercamera/s. In some embodiments rolling shutter cameras are used andoptionally temporal distortion is compensated.

Optionally, a smeared path of one or more than one marking (e.g. highcontrast marking) are mounted on the stylus during vibration isextracted from collected images.

FIG. 10 is a schematic diagram of an embodiment where stylus movement isoptically tracked. A light source, for example a LED 1068 mounted tomain body 1020 illuminates, stylus markings which, in some embodimentsare selected so that reflection to the imager final optical element isspecular and with known geometry relative to position. In someembodiments stylus markings are for example, specular spheres 1066and/or a bump (e.g. 0.5 mm diameter spherical bump) 1070 mounted tostylus 1018. The dashed arrows emanating from LED 1068 show the lightpath from LED to camera/s 1030: LED light is reflected off of bump 1070to mirror 1056 and is reflected from mirror to camera/s 1030. Camera/s1030 see an image of a tiny very high contrast specular spot over bump1070. The location of the specular spot is on the patch of bump 1070with a normal parallel to the bisector of the angle formed by the lightray originating from LED light source 1068 to the specular spot andlight ray reflected from said specular spot to mirror 1056 and camera1030 (schematically indicated by dashed arrows). In some embodiments,estimation of the spherical bump 3D location from collected images takesinto account the effect of slight movements of the imaged spot locationover the specular bump.

In some embodiments, measurement is from a portion of collected images,a region of interest (ROI) which surrounds the stylus location. In someembodiments only the ROI is imaged (imaging is of a portion of thecameras FOV). A prospective benefit of using a ROI is reduction inimaging and/or processing. In some embodiments, the ROI is changed withtime in order to track the moving stylus. In some embodiments, if thestylus is not found in the ROI, the ROI is enlarged.

In some embodiments the location of a vibrating stylus relative to mainbody is tracked using two fast cameras, e.g. cameras operating at a rateof 120 frames per second or higher, which image the vibrating stylusmarkers with a small (e.g. about 30% or about 20% or about 10% or about1% of the image size) region of interest (ROI) for stylus tracking at aneven higher rate for example about ×5 or about ×10 or about ×100 thefast cameras base images rate e.g. 1200 frames per second. In someembodiments images of the whole camera/s FOV can be taken at lower rate,for instance at 60 frames per second while the imaging at the ROI arecollected at a high rate.

Device with Rounded Stylus Tip

The stylus tip can have various shapes, depending, for example, on oneor more of desired effect, spacing between teeth, angle of access,damage to gums and/or accuracy considerations. For example, the tipshape can be a cone shape, an inverted cone shape, a flattened shape, aspherical shape or another rounded shape such as an ellipsoid. In thisand other embodiments the tip can be rounded, for example, spherical ornon spherical. As an example, spherical tip shapes are described hereinwith respect to some embodiments. FIG. 7 is a schematic diagram of anembodiment with a spherical stylus tip. FIG. 7 illustrates an embodimentfor tooth measurement below the preparation finish line 708 and/or of anatural tooth emergence profile, and/or below a line of maximum toothcross section, and/or of tooth surfaces where the angle of the tooth tothe apical-coronal direction increases. FIG. 7 illustrates an embodimentwhere stylus 718 has spherical stylus tip 722 with a wider diameter thanthe stylus. For example, as illustrated in FIG. 7 stylus 718 and stylustip 722 are in position to measure a tooth surface below or apical ofpreparation finish line 708.

A potential benefit of embodiments where the stylus tip is wider thanthe stylus body is that the tilt angle θ (illustrated in FIG. 3B) of thestylus to the horizontal may be reduced for subgingival measurements.

A potential benefit of measuring the emergence profile of the naturaltooth below the preparation finish line is that prosthetics constructedusing the emergence profile measurements which match or blend with theemergence profile have a smooth surface junction with the natural tooth.Introduction of a prosthetic which has a smooth surface junction withthe natural tooth does not provide a gap or crevice for bacteria togrow.

In some embodiments other stylus tip shapes collect measurements apicalof the preparation finish line, for example a stylus with a spade shapewith a flattened tip which is wider than a stylus body portion adjacentto the tip is inserted easily by inserting the flattened side of the tipparallel to the tooth surface. The spade shaped stylus tip is thenrotated 90° for measurements. A conic stylus tip or other shapes knownin the art for stylus scanner tips are also envisioned and encompassed.

FIG. 7 also illustrates the ability of many described embodiments tomeasure visually obscured tooth surfaces: Stylus tip 722 is submergedunder fluid 752. Fluid 752 can be from crevicular fluid in the sulcusand/or gingival bleeding caused e.g. damage to the gingival tissueduring tooth preparation and/or periodontal inflammation. A potentialbenefit of the above described ability to measure under fluid isimproved speed over subgingival measurement existing techniques wherebleeding or other fluids must be absorbed or prevented beforemeasurement is possible.

FIG. 7 also illustrates an embodiment of cameras 730, 732positions/orientations within/on main body 720. Cameras 730, 732 areangled towards stylus 718 so that cameras' FOV are orientated towardsthe tooth and stylus. In some embodiments, the stylus and/or stylus tipis constructed of a softer material than tooth material (e.g. enamel,dentine). In some embodiments, scanning a tooth with the stylus does notscratch the tooth surface. In some embodiments, the stylus isconstructed of metal coated, at least at the stylus tip, with a softcoating where the soft coating is made of a material softer than toothmaterial (e.g. enamel, dentine).

Mirror Imager Final Optical Element

Optionally, SGMP 816 can include an angled (or folding) mirror 856. FIG.8 illustrates a mirror 865, an imager final optical element which, asdescribed above, fits into the patient's mouth and is in close proximity(e.g. within 4 cm of) to stylus tip 822. Mirror 865 reflects a FOV (e.g.including prepared tooth 804 and/or stylus 818 and/or mouth structure/s)to an imager or camera/s 830 which allows the imager or camera/s 830 tobe at a larger distance from the tooth than the distal end of stylus818.

Optionally, a main body entrance aperture 858 is covered by atransparent window (not shown in FIG. 8), such as a glass window. Thetransparent window protects the mirror from liquids (e.g. droplets,spills) and/or dirt and can be cleaned easily. In some embodiments thewindow and/or other optical elements (e.g. camera/s) include one or moreheating system (e.g. to heat the window and/or camera lens) to preventcondensation from obscuring imaging.

Sensors

In some embodiments, SGMP 816 includes one or more sensor. FIG. 8 is aschematic diagram of an embodiment including a sensor. Sensor/s arelocated for example, on the stylus (including stylus body, stylusproximal end and the stylus tip) and/or on the main body and/or mountedto a mouth or facial surface (e.g. tooth, gum, lip, cheek) and/ormounted to another component (e.g. pointer, alternative dental tool).

In an exemplary embodiment of the invention, stylus 818 is connected tomain body 820 through a sensor 854. In some embodiments sensor 854 is aload cell. In some embodiments load cell 854 measures the applied forceon stylus 818 connection to main body 820 in up to three directions. Insome embodiments the location of the stylus tip 822 (stylus deflection)relative to main body 820 (stylus end location) can be determined fromload cell measurements. In some embodiments stylus 854 moves withrespect to main body 820 and load cell 854 measures stylus movement withrespect to main body.

In some embodiments measurements of stylus deflection are used todetermine stylus tip location. In some embodiments, to determine stylustip location from stylus deflection measurements, the measurements arecalibrated. For example, in one embodiment, the force measured by theload cell is calibrated with possible deflections of the stylusincluding stylus tip lateral and/or vertical movement. In an exemplaryembodiment of the invention, a jig is used to provide the deflections.

In some embodiments mechanical stylus deflection measurements (e.g. loadcell measurements) can be made at high sample rates e.g. 10 kHz for loadcells. High rates of stylus deflection measurement facilitate rapidscanning (and measurement) of subgingival surfaces with the stylus tip822. A potential benefit of using mechanical measurements totrack/determine stylus tip location is that mechanical measurements canpartially or fully replace stylus optical tracking. In some embodimentsmechanical measurements are used to track stylus tip location at a highrate e.g. 10 kHz sample rate (compared to a 60 Hz sample rate for common60 FPS imagers).

In some embodiments combining mechanical measurements or tracking of thestylus tip with imaging where the stylus tip location is not determinedfrom images (even where low rate mechanical measurements (e.g. below 10kHz) are used) which reduces the image processing requirements on theimager and/or the resolution and/or sample rate of images. In someembodiments mechanical stylus measurements, such as those collected byload cell 72 are combined with measurements/mode (e.g. from an existingcurrent intraoral scanner) to generate a tooth model includingsubgingival tooth regions. Combining mechanical stylus measurements withan existing model (as opposed to combining image measurements) reduceimage processing as alignment is of mechanical measurements to a model,not of multiple images to a model.

Optionally, the stylus end location can be alternatively or additionallydetermined from stylus deflection measurement by one or more straingauge (as described in more detail with reference to FIG. 9A below). Insome embodiments strain gauges can be applied to the stylus at severallocations (e.g. sensors 921 on FIG. 9A). In some embodiments, the bendsin a known manner. In some embodiments, the stylus is designed to have aweak point (e.g. where stylus thickness is smaller than one or moreadjacent stylus portion), where most bending occurs. In some embodimentsstylus deflection is measured by a strain gauge located at the weakpoint.

In some embodiments stylus deflection can be measured using acombination of measurement methods, such as optical measurement ofmarkers (as described previously) and mechanical measurement (e.g. byload cell).

In an exemplary embodiment stylus 818 scans tooth 804 vertically whilstremaining in contact with the tooth surface: The stylus body is moved inthe vertical (apical-coronal) direction and the stylus tip is deflectedby the tooth following the surface of the tooth apically (downward). Thevertical scan can be, for example 2 mm long at 50 Hz. In someembodiments, whilst the stylus is scanning vertically, the stylusdeflection is measured at a high rate e.g. by load cell 854 at 10 KHz,such that for an exemplary 50 Hz scan cycle, for each vertical scancycle the location of 200 points is measured.

In some embodiments, the user moves the vertical scanning (or vibrating)stylus horizontally around the tooth (e.g. following path 219illustrated in FIG. 2D), at a rate compatible with the imager scanningrate. For example, if the imager scanning rate is 10-60 frames persecond, to image at least 500 scan positions around the tooth, thestylus is moved around path 219 in 8-50 seconds.

In some embodiments the SGMP includes a Position Sensitive Diode (PSD)(e.g. for optical scanning). In some embodiments the PSD is attached tothe main body. In some embodiments the SGMP includes one or moreproximity sensor e.g. capacitive proximity sensor, optical proximitysensor (e.g. for stylus tracking). Optionally, the SGMP includes one ormore linear encoder/s e.g. capacitive encoder, optical encoder and/orone or more LVDT (linear variable differential transformer) sensor (e.g.for stylus tracking). Optionally, the SGMP includes magnet/s orelectromagnet/s (DC or AC modulated) mounted to the stylus (e.g. forstylus tracking).

Optionally, measurement from sensor/s can be used to verify that thestylus tip is in contact with the tooth subgingival surface.

In some embodiments verifying contact of the stylus tip with the toothis by a measure of stylus deflection. In some embodiments stylus contactwith the tooth subgingival surface is verified for a stylus deflectiondirection or a range of stylus deflection directions. In someembodiments stylus contact with the tooth subgingival surface isverified when stylus deflection direction is perpendicular to toothsurface: The tooth surface direction can be extracted directly from anupdated tooth model and/or from the direction of stylus tip movementwhen scanning around the tooth (e.g. following path 219 illustrated inFIG. 2D.) In some embodiments a specific stylus deflection or pressurerange indicates that the stylus is in contact with the tooth. In someembodiments stylus deflection is measured by one or more strain gauge onthe stylus and/or by a load cell and/or by other methods of measuringstylus deflection and/or force as described above (e.g. optical), and/orother methods known in the art.

In some embodiments verifying contact of the stylus tip with the toothis by verifying a magnitude and/or direction measure of force applied tothe stylus tip. In some embodiments, contact of the stylus tip with thetooth is verified for a threshold applied force magnitude (e.g. measuredby load cell 854 on FIG. 8 and/or measured by a force sensor at thestylus tip) at the stylus tip. In some embodiments, contact of thestylus tip with the tooth is verified for an applied force direction,which depends on the location of the stylus with respect to the tooth(e.g. position of stylus on path 219 illustrated on FIG. 2D). In someembodiments the applied force direction is calculated (e.g. byprocessing application 1280 on FIG. 12) from real-time images.

In some embodiments verifying contact of the stylus tip with the toothis by verifying that the stylus is within a depth and/or height range(e.g. stylus tip depth with respect to a preexisting model, stylus depthwith respect to a marker on the tooth).

If the stylus body contacts a tooth surface (e.g. when measuring belowthe preparation finish line, between adjacent teeth) stylus deflectionmeasurement to verify stylus tip contact with the tooth surface canprovide a false positive. In some embodiments one or more estimates ofstylus location in relation to a known teeth model is used to ascertaina risk that the stylus body touches a tooth surface (e.g. prepared toothsurface above the surface being measured) and is used to discount falsestylus contact verification. In some embodiments an algorithm identifiesfalse stylus contact verification using the stylus tilt angle and/or ameasured tooth gradient/slope of decent (in the apical direction) duringscanning; e.g. if the gradient zeros or is less than expected,indicating that the stylus tip is being prevented from reaching thetooth surface (e.g. by stylus body), the algorithm indicates a falsecontact verification.

FIG. 9A is a schematic diagram of an embodiment with a sensor located atthe stylus tip. FIG. 9A illustrates an embodiment with a sensor 923 atthe stylus tip and sensors along stylus length 921. In some embodimentssensors 921 are strain gauges. In some embodiments sensor 923 is a forcesensor such as load cell, strain gauge. The force sensor located at thestylus tip 923 measures the force applied at the tip and not over all ofthe stylus as, for example when measuring stylus deflection at stylusbase or over the whole stylus body.

In one embodiment contact of the stylus tip with the tooth is verifiedusing a two part stylus where the stylus tip moves with respect to asecond stylus part. Imaging or tracking of this movement, optionallyassisted by markers, can be used to verify stylus tip contact with thetooth surface.

FIG. 9B is a schematic diagram of an embodiment with a mechanism foroptical verification of contact between the stylus tip and subgingivalpreparation margin. Stylus 918 is hollow and includes an internal post960, optionally coaxial, that is connected to stylus tip 922. Post 960is slightly smaller in diameter than the inner diameter of hollow stylus918 and can slightly move laterally and/or vertically) within hollowstylus 918 a when force is applied to stylus tip 922. In someembodiments movement of internal post 960 is be viewed and measured bycameras 930 and 932.

Optionally, measurement of post movement (e.g. lateral movement) is byviewing a marking 962 on post 960 through a window 964 in hollow stylus918 a. In some embodiments hollow stylus 918 a has multiple windowscorresponding to multiple markings on post 960. Optionally, the windowsinclude markings (e.g., graduations and/or edge markers) so they can beidentified in the acquired images of the stylus. The windows in hollowstylus 918 a can be used in addition to or instead of stylus markings.

Optionally, post movement (e.g. lateral movement) is measuredelectrically: In some embodiments post 960 is electrically isolated fromhollow stylus 918 a and electrical measurement of post movement withrespect to hollow stylus is, for example by measurement of thecapacitance between post 960 and hollow stylus 918 a.

In some embodiments filling a gap 919 between internal post 960 andexternal stylus 918 is filled with a flexible material, e.g. silicone orRTV (Room Temperature Vulcanizing) silicone which provides stability tostylus tip 922 whilst allowing movement of post 960 relative to hollowstylus 918.

Lateral Actuation

In some embodiments a stylus connection to the main body is using amovement mechanism which allows the stylus tip to move and/or amechanism which causes it to move horizontally. Exemplary movementamounts are 2 mm, 1 mm, 0.5 mm and/or intermediate or smaller amounts ofmovement, optionally symmetrical. Optionally, movement is used to assistthe stylus in following a subgingival tooth surface contour e.g. duringvertical stylus scanning. During vertical scanning, the stylus tip canbe caught by a step like subgingival preparation margin and not descendapically of the step. In some embodiments the SGMP includes a movementmechanism which moves the stylus laterally when the stylus encounters ahigh angle feature (e.g. subgingival margin step). In some embodiments amovement mechanism to move the stylus laterally or horizontally is aflexture. In some embodiments the movement mechanism includes a verticalactuator. In some embodiments the vertical actuator can move and/orvibrate stylus tip 822 vertically by 1-5 mm. In some embodimentsvertical stylus movements are less than 15 mm or less than 10 mm andlateral movements are less than ±10 mm or less than ±5 mm

In some embodiments the movement mechanism comprises a flexture thatincludes a vertical actuator (for vibrating stylus tip vertically by 1-5mm) and two tilting actuators (optionally with electrical or opticalencoding) which can move the stylus tip laterally by ±1 mm. In someembodiments the stylus tip is scanned vertically over tooth surfacecontour whilst preventing the stylus tip from colliding and/or beingcaught by into sharp angled features (e.g. a step shaped preparationmargin) by moving the stylus laterally to avoid the sharp angledfeature/s. In some embodiments avoiding contact or scanning of sharpangled features is by control of the lateral actuators using real timeinformation of the force applied to stylus tip (e.g. using forcesensor/s as described above), and/or a preexisting tooth model (e.g. atooth model indicating a likelihood of and/or location of a step shapedcontour). Optionally, a scanning control software determines and/orpredicts (e.g., using prediction methods known in the art) where thestylus may get caught and moves the stylus away from such a problemlocation.

Side Attached Stylus

FIG. 11 is a schematic diagram of an embodiment with a side attachedstylus: Stylus 1118 is connected to main body 1120 to the side of theimaging port/window. In this example, stylus 1118 is L-shaped includinga measurement portion (vertical in FIG. 11) and an attachment portion(horizontal in FIG. 11). In some embodiments, as illustrated in FIG. 11,an angle of connection between stylus attachment portion and measurementportion is approximately 90°. In some embodiments the angle ofconnection measurement potion of stylus 1118 is tilted and is at more orless than 90° to the attachment portion. Stylus 1118 connects to mainbody 1120 through housing 1154. In some embodiments housing 1154includes a load cell and/or other force sensor/s.

Optionally, stylus 1118 has strain gauges along the stylus length (notillustrated). In some embodiments the load cell and/or optional straingauges measure stylus deflection as described above. In some embodimentsL-shaped stylus 1118 vibrates vertically, as described above. In someembodiments housing 1154 includes a mechanism, (e.g. a flexture) whichallows stylus tip 1122 to vibrate vertically 0.2-10 mm or 1-5 mm and tomove horizontally at least 0.1 or at least 0.5 mm or at least 1 mm or atleast 5 mm in each direction. In some embodiments housing 1154 includesan actuator that can cause stylus tip 1122 to vibrate vertically 0.2-10mm or 1-5 mm. In some embodiments vertical stylus vibration results invertical and lateral deflections of up to 5 mm or up to 1 mm or up to0.5 mm. In some embodiments housing 1154 includes an actuator that cancause stylus tip 1122 to vibrate vertically at amplitudes of up to 5 mmor up to 10 mm or up to 20 mm and measure larger deflections. In someembodiments housing 1154 includes an actuator that can cause stylus tip1122 to vibrate vertically and to move horizontally to track the toothsurface.

A potential advantage of connecting stylus 1118 at the side of main body(and embodiments where the imager is not attached to the stylus asillustrated in FIG. 20) 1120 is that an optical path between tooth 1104and the imager is not obscured by the connection between the stylus andthe main body. In some embodiments, as described above, the imager, e.g.camera/s 1130, collects images which are used to track stylus 1118.

Optionally, the stylus can be disconnected from the main body. In someembodiments SGMP includes a mechanical connector element (e.g. dove tailshaped joint, ball and socket joint, optionally with a hexagonalconnector preventing rotation) that enables easy connection anddisconnection of the stylus from the main body. In some embodiments theconnector includes a release button (e.g. release button 1999 on FIG. 9)which, when pressed by a user releases and/or opens the connector. Insome embodiments the mechanical connector element ensures a goodconnection of the stylus to the main body with small movement (<10 nm)of the stylus (e.g., at the connection point and/or stylus tip) and mainbody relative to each other (due to mechanical connector tolerances)during measurement. In embodiments where the stylus and main body havesmall movement relative to each other during measurement, stylus tiplocation measurements can be using force measurements as describedabove. In embodiments where the stylus is tracked optically largermovements between stylus and main body may be tolerated.

A potential benefit of a removable stylus is that the stylus may besterilized by autoclave, as the current common practice for dentalprobes. This is in contrast to sterilization of existing intraoralscanners which is generally achieved by cleaning of the scannerintraoral portion with alcohol/chlorhexidine/peroxide wipes, sinceautoclaves can damage cameras or other components. Another potentialbenefit of a removable stylus is that the stylus can be disposableand/or the stylus can be replaced in the event of damage or naturalwear, without requiring the SGMP itself to be replaced.

A potential advantage of a side connection is that a cover (e.g., acondom) may be placed over the SGMP and not interfere with the stylusconnection, which is further away from the SGMP tip.

Disposable Parts

Optionally, portion/s of the device are disposable. In some embodimentsthe stylus is disposable. In some embodiments the device includes adisposable imager cover. In some embodiments the stylus can be easilyconnected and/or disconnected to and from main body. In some embodimentsan easily connectable/removable stylus is disposable.

In some embodiments a disposable cover, which is replaced betweendifferent patients, covers at least one camera or optical windowreducing the risk of contamination between patients. FIG. 11 illustratesa cover 1174 which can be disposable. Cover 1174 includes a covertransparent portion 1176 over window 1158.

In some embodiments the stylus is connected to (or integral with) acover outside of the cameras viewing area (e.g. at the side) with thehousing connecting the cover and main body. In some embodiments stylusis connected to a cover forming one disposable part. In some embodimentsstylus is connected to a cover and stylus and cover dismantle into twoor more units of which one or more unit is disposable.

In an exemplary embodiment of the invention, a load cell for measuringstylus movement is provided on the SGMP body, adjacent to an expectedlocation of the stylus. When a cover with a stylus is placed on theSGMP, the stylus can be read by the load cell (and/or other sensor).Optionally, the stylus includes a portion which extends past the covertowards the SGMP. Such an extension may assist with alignment and/orrelative locating. Optionally or alternatively, other matching featuresbetween the cover and the SGMP body are used for locking and/oralignment between the cover and/or stylus and the SGMP body. In oneexample, the matching feature comprises a ring (e.g., a notch and amatching groove).

In some embodiments, the disposable part includes only plastic parts,possibly with some metal used for ensuring desired rigidity. Optionallyor alternatively, the disposable parts include some electronics (e.g.,sensors, amplifiers for the sensors and/or illuminators, optionally withpower supplies). In such embodiments, the electronics optionally includeone or more contacts which match one or more contacts in the SGMP, forexample, on a body thereof and/or in a socket thereof. Optionally oralternatively, wireless link methods, such as Bluetooth are used forcommunicating between the disposable electronics and the rest of theSGMP. In some embodiments, the disposable part may include opticalelements (e.g., a reflector and/or a lens). In some embodiments, animager is included in the disposable parts.

Tooth Model

In some embodiments measurements including imaging and stylusmeasurements are used to produce a tooth model. This tooth model may,for example, be used as is or may be registered to and/or combined witha separately acquired tooth model.

In some embodiments, estimate/s of stylus tip position with respect tosupragingival tooth portions are used to generate a model of asubgingival surface topography of the tooth. In some embodiments imagesof visible tooth portion/s are combined with subgingival measurements tocreate a model of subgingival and supragingival surface topography ofthe tooth.

Optionally, gingiva position with respect to supragingival toothportions is estimated from images, for example, by identifying gingivatissue, e.g., based on color, and calculating a location in the imagecoordinates. In some embodiments gingiva position with respect tosupragingival tooth portions is estimated from preexistingmodels/measurement (e.g. from digital imaging, CT, MRI scan). In someembodiments gingiva position with respect to supragingival toothportions is used to generate a gingival (or gum) line on a model of thesurface topography of the tooth.

In some embodiments a preparation finish line is indicated on the toothmodel e.g. to assist matching of a crown finish line to the preparationfinish line. In some embodiments a preparation finish line is estimatedfrom a tooth surface topography model (e.g. by identifying a stepshape). In some embodiments the preparation finish line is estimatedfrom a subgingival margin tooth surface topography model. In someembodiments the preparation finish line and/or a prosthetic finish linecan be added to the tooth model by the user manually scanning the stylustip over the preparation finish line or over a desired prosthetic finishline. Optionally, the user controls a user interface (e.g., a touchscreen, mouse based interface and/or a button) to indicate that a styluscontact is for marking rather than and/or in addition to measurement.Such a marking is optionally added to the model and may be viewed and/orotherwise used downstream for example, by a technician. Optionally, thisenables a dentist to decide and/or provide input on the size and shape(e.g., does it surround the whole tooth or not and where) of the crown,rather than only a technician applying his own judgment.

In an exemplary embodiment of the invention, such marking may be used aspart of scanning process, for example, to indicate to the system where abetter scanning is needed and/or where a step in the subgingival area isformed. Optionally, the system uses such markings to ensure thatsufficient data points are acquired where needed for reconstructing atooth model showing those parts for which an accurate model is neededaccording to the markings. Optionally or alternatively, such marking isdone on an image on a screen, for example, on an image of a preexistingtooth model.

Combining Models

FIG. 15 is flow chart which shows a method for alignment of one or moreimages and/or one or more models, in accordance with an exemplaryembodiment of the invention. In some embodiments images are aligned toprovide 3D modeling, for example, to combine multiple stylusmeasurements with their associated images, the images are aligned (insome embodiments creating a 3D model). In some embodiments, two or moretooth models (e.g. tooth models from different measurement devices) arecombined.

FIG. 15 illustrates combining a first image or model 1502 with a secondimage or model 1504 to generate a 3D model 1512. The models (or imagesor image and model) 1502 and 1504 are aligned. For example, one or moreof 2D pattern matching 1506, marker matching 1508 and 3D featurematching may be used. Other image alignment methods and/or surface modelalignment methods and/or image to surface alignment methods may be usedas well.

In some embodiments 2D pattern matching is, for example, of marks orpatterns or features of a tooth surface. In some embodiments 2D patternmatching is, for example, matching a light pattern illuminated onto atooth (and/or teeth and/or mouth structure) e.g. by a pattern projector.In some embodiments matching is of a light pattern is by identifyingspatial and/or wavelength and/or temporal coding of the light pattern inat least one image and fitting the pattern to a known reference patternor to light patterns in other images.

In some embodiments 3D matching is, for example, of tooth 3D surface/s(including the prepared tooth and/or other tooth/teeth). In someembodiments marker matching is when marker/s in both image/s and/ormodel/s are used to combine the image/s and/or model/s. Althoughdescribed with reference to combining two image/s/model/s in someembodiments the method for alignment described above is used to alignmore than two image/s and/or model/s (e.g. combining multiple imagescollected in a tooth scan).

In some embodiments marker/s and/or fiducial/s can be attached (e.g.,marked using a marker or attached by adhesive) to the prepared toothand/or other teeth and/or other mouth structures. In some embodimentsthe marker/s are used to combine or register a model of the visible partof the tooth, such as the supragingival part of the tooth (e.g. measuredby current available intraoral devices, scanned impressions) with thesubgingival or invisible part of the tooth (e.g. measured using one ormore of the methods or embodiments described in this document).

A potential benefit of combining two models, as described above, is thatthe SGMP can be simpler and/or smaller and/or enable faster subgingivalscanning and/or lower cost since, for example, the imager, in someembodiments, identifies marker/s and does not measure a full model ofvisible part of the tooth (e.g. using pattern projection and highresolution imaging).

In some embodiments a supragingival model of a prepared tooth includingmarker/s and optionally of other mouth structures such as adjacent teethis acquired. The supragingival model is acquired for example by usingintraoral scanners available on the market or by making a standardimpression and converting it into a digital 3D file. Optionally, theSGMP is used for acquiring images for reconstructing a model of thesupra-gingival portions of the tooth as well.

In some embodiments the SGMP is used to scan the subgingival toothmargins and measurement of subgingival points on the tooth, as describedabove, is with respect to the marker/s. In some embodiments an imager isused for estimating marker/s position with respect to the main body. Insome embodiments, for example two cameras are used or a single camerawith two or more viewing angles (e.g. plenoptic camera). In someembodiments a portion of the camera/s field of view, a Region OfInterest (ROI) which includes markers is imaged at a high rate, (e.g.250 Hz). In some embodiments the location of marker/s in camera/s imagesare tracked (e.g. by a processing application) and the ROI is updatedduring scanning so that the ROI includes the marker/s throughoutscanning

In some embodiments the subgingival margin 3D information (subgingivalmodel) is combined or registered with the supragingival tooth (or teeth)model using marker information to provide a subgingival andsupragingival tooth model. In principle, to combine two 3D modelstogether, three markers or fiducials are needed. However, a singlemarker or fiducial on the tooth (or other mouth structure) with at leastthree features can provide three anchoring points for combining the two3D models (supragingival and subgingival) together. In some embodimentsthe marker includes more or fewer than three features. In someembodiments natural feature/s of the tooth are used as one or moremarkers.

In some embodiments supragingival scanning (e.g. by intraoral scanner,standard impression scanning, CT) is not able to provide markerinformation in the model (e.g. color contrast markers cannot be measuredby many existing intraoral scanners as existing intraoral scannersgenerally provide 3D measurement without color contrast information),and produces a marker-free supragingival model.

In some embodiments SGMP stylus is scanned over some supragingival toothportions of prepared tooth and/or neighboring tooth/teeth for example byscanning several lines and/or measuring points across or around thevisible tooth e.g. scanning a cross over the prepared tooth. The SGMPthen takes subgingival measurements with respect to the marker/s (asdescribed above). The supragingival SGMP measurements (scanned lines ormeasured points) relative to the marker/s position are used to combinethe marker-free supragingival model (e.g., acquired using one or more ofintraoral scanner, scanning standard impression, CT and/or MRI) with thesubgingival model. In some embodiments measuring (e.g. scanning linesand/or measuring points) on at least one neighboring tooth reduce arotation error in alignment between the marker-free supragingival andsubgingival models.

As can be seen, in some embodiments, scanned points are added to anexisting supragingival model. In other embodiments, the collection ofscanned points are themselves joined to form a model which may then bealigned with an existing model. In some embodiments, both models areacquired simultaneously.

In some embodiments, a thick marker (e.g. 50 μm or more thick) isattached to the tooth before supragingival scanning when scanning iswith a scanner not able to provide marker information in the model. Insome embodiments, the thick marker is attached to a coronal part of theprepared tooth, where the accuracy of the scan is lower. The thickmarker appears as a 3D feature in the marker-free model which, in someembodiments is used to combine the marker-free supragingival model asdescribed above (e.g. obtained from a device that cannot capture printedmarker/s) with the subgingival model (from SGMP measurements). In someembodiments the thick marker/s are removed from the combinedsupragingival and subgingival model in model post-processing e.g. byprocessing application (described below). In some embodiments the thickmarker is removed and the tooth area previously under the marker isre-scanned providing a partial supragingival model for combining withthe supragingival and subgingival models to provide a tooth model whichincludes the area under the thick marker.

In some embodiments, while the supra-gingival model is a surface model,it may have images registered therewith and/or include image and/orcolor information. These images may be used for aligning with imagesacquired by the SGMP during scanning.

Drill Stylus

Optionally, the stylus is a dental drill. In some embodiments images arecollected during drilling and/or grinding preparation of the tooth. Insome embodiments the drill tip is tracked using methods described aboveduring preparation of the tooth providing the shape of the preparedtooth 204. Optionally, the drill can have color contrast markings,similar to markings 234 (illustrated in FIG. 2A) or other markings moresuited to dental drills (e.g. a pattern printed over or in between drillabrasive powder particles). Optionally, the location of preparationmargin finish line 108 is not collected when tracking the drill. In someembodiments the preparation finish line is measured using a stylussimilar to those described above. In some embodiments, the drill itselfwhen it is not rotating is used as stylus, the drill tip forming stylustip 222 for measurements of preparation finish line 108. In someembodiments the drill tip or end is replaced with a stylus similar tostylus 218, optionally including stylus markings 234. Other devices andmethods described above can be used for drill tracking.

Exemplary Implementations

FIG. 13 is a flow chart that illustrates an exemplary method forcreation of dental prosthetics, in accordance with an exemplaryembodiment of the invention. The dentist prepares the tooth or teeth(1300) to which the prosthetic will be affixed. After preparation,optionally, supragingival measurements of the prepared tooth arecollected using another device or method, e.g. impression, digitalimpression, CT, MRI (1302). Optionally a gum receding material (e.g.,retraction paste) is applied to the gingiva to cause it to retract awayfrom the tooth. Optionally or alternatively, other materials, such as toreduce bleeding, are used. The SGMP device is then turned on, and thestylus is put into a starting position (1304). SGMP then collectsmeasurements (1306). Measurements can be, for example, optical (e.g.images), mechanical using stylus tracking etc. (e.g., as describedabove). In some embodiments, for example as described above, collectingmeasurements involves the user guiding SGMP around the tooth.Optionally, the user can then check the tooth (1308) and/or prostheticmodels produced e.g., through a user interface, such a computer with adisplay and optionally a mouse and/or keyboard. Optionally, the user canmanually add a prosthetic finish line to the prosthetic model throughthe user interface and/or by marking desired prosthetic finish lineand/or parts thereof, using the stylus, on the tooth. The user thensends the prosthetic model for construction (1310). Once the prostheticis received by the user, it is fitted/attached to the prepared tooth(1312). The supra gingival model and sub-gingival model are optionallycombined by the user (e.g., using local processing or sending a requestto a remote server). Optionally, the user can view the combined model tomake sure that the model is correct and optionally modify the combiningmanually, for example, by rotating, scaling and/or translating a modeland/or by defining the process to used for combining overlapping partsof two models. Alternatively, they may be combined by a clinic whichmanufactures the tooth. Optionally, the combining is at a remote server,which may receive the data from the user, clinic and/or both.Optionally, usage of this remote server is charged.

In some embodiments, the stylus holds a portion of the gingiva away fromthe tooth at each measuring point around the tooth (as described above).Images are collected of the tooth, including subgingival portions. Amodel of the tooth (tooth model) can be constructed from the collectedimages. In an exemplary embodiment of the invention, this can use adevice which is otherwise adapted only for supra-gingival imaging.Optionally or alternatively, the device is programmed to recognize thestylus (or other tool, such as a hook, used to retract the gingiva).Optionally, the recognition is used to remove the stylus so that it isnot formed into the model. Optionally or alternatively, the recognitionis used so that location where sub-gingival portions are visible can beidentified (e.g., at the tip of the stylus). Optionally, the deviceindicates if the entire sub-gingival portion was imaged. In general, itis noted that if a device is made aware of the extent and/or generalshape of the sub-gingival areas (e.g., using a CT model or manual entry,such a device (SGMP or other scanner) can automatically detect ifsufficiently accurate and/or dense samples are acquired of the areas ofinterest.

In some embodiments, the stylus holds a portion of the gingiva away fromthe tooth at each measuring point and the stylus is scanned around thetooth preparation finish line. Estimation of the position of the tip ofthe stylus with respect to the tooth portions visible to the imager foreach point measured around the tooth is used to add a preparation finishline to the tooth model constructed from the collected images.Optionally, the user is prompted to perform such a scan by the userinterface (e.g., visible and/or audio display).

FIG. 14 is a flow chart which shows a method and algorithm for creatinga 3D model of a tooth, in accordance with an exemplary embodiment of theinvention. The SGMP stylus tip is placed into a starting position incontact with a surface of the tooth 1400. The SGMP then collects imageswith the imager 1404. From the collected images, the dimensions (surfacetopography) with respect to the imager of a tooth portion visible(visible tooth portion) to the imager are estimated 1406.

In some embodiments the visible tooth portion is visible to two cameras.In some embodiments the visible tooth portion is a visible to at leastone camera and a pattern projector. In some embodiments the visibletooth portion is visible to at least two viewing angles of a plenopticcamera. In some embodiments the visible tooth potion is visible to atleast two apertures of a multi-aperture camera. In some embodiments atooth portion including visible feature/s and/or marker/s is visible toat least one camera.

The estimation of the dimensions of the tooth portion is then registeredwith a tooth 3D model 1408. Optionally or alternatively, the images arecombined into a model, for example, using tooth model building methodsknown in the art. Optionally, if a part of the model is corrected, thesame correction may be applied to the sub-gingival portion whoseposition was simultaneously acquired. In some embodiments, thesubgingival portions are acquired after at least data of a coarsesupragingival model is acquired and/or reconstructed.

In some embodiments feature/s and/or marker/s locations are known apriori or feature/s/marker/s location images from other viewing anglesenable feature/maker location estimation, the location offeature/s/marker/s are registered with tooth 3D model. In someembodiments, the tooth 3D model is preexisting for example, from anothermethod/device (e.g. traditional impression, digital impression, CT,previous measurements using SGMP). In some embodiments the tooth 3Dmodel is generated by the SGMP during measuring/scanning. Optionally,registration is by matching marker/s which can be physical marker/s onthe tooth and/or tooth features that appear in 3D model (3D matching)and/or tooth features that appear in imagers 2D images (2D patternmatching). Optionally, stylus end location (stylus tip location withrespect to cameras) measurements are collected using methods describedabove for example by force sensor (e.g. load cell, strain gauge 1409).The location of the stylus tip with respect to the visible tooth portion(stylus tip location) is then estimated 1410. The stylus tip location isthen registered with the tooth 3D model 1412. If enough tooth locationshave been measured 1414 scanning is finished and the 3D tooth model iscomplete 1416. If more tooth locations are to be measured the SGMPstylus tip is moved around the tooth to a new location 1402 wheremeasurements 1404, 1409, estimations 1406, 1410 and registration withtooth 3D model 1408, 1412 are repeated for the new location.

Optionally, the user receives an alarm or other indication when scanningis complete. Optionally, SGMP can indicate to the user to conductadditional scanning and/or areas of the tooth to scan. Optionally, auser display an image of a scanned tooth model with an indication ofmissing tooth portions or other tooth portions to be scanned.

Optionally, in some embodiments, the method described in FIG. 14 can berepeated, with stylus measurements for more than one tooth whilstregistering with a model, to create 3D models of more than one tooth,for example when making measurements for a bridge. Optionally, in someembodiments, the method can include taking stylus measurements for onetooth whilst registering measurements and collecting images of othermouth structures e.g. other teeth, gums.

Optionally, in some embodiments, the user generates a prosthetic finishline and/or a preparation finish line from SGMP stylus tip locationswhen scanning around the tooth (e.g. the user selects a user interfaceoption to ‘define prosthetic finish line’ and then scans the stylus tiparound a desired prosthetic finish line).

Optionally and alternatively, more than one measurement at a time isregistered with the tooth model (e.g. after scanning) Optionally SGMPmeasurements can be collected before collecting or accessing a‘preexisting’ model.

Optionally, after scanning is complete, a processing application usesthe gathered images and stylus locations to provide a better accuracymodel. This may be useful if, for example, the model is generatedincrementally. An optimization process, for example, iterativelyapplied, can modify parts of the model so that the overall error isreduced. In one example, an optimization algorithms that uses some orall the acquired information (e.g., global optimization or IterativeClosest Point (ICP) algorithm) is used to minimize the differencebetween clouds of points that are generated by different parts of thescanning process. ICP is optionally used to reconstruct 2D or 3Dsurfaces from different scans. In an iterative method, the existingmodel is taken as a starting point and then “corrected” using theacquired data so as to, for example, reduce errors and/or artifactstherein. This process is optionally repeated.

In an exemplary embodiment of the invention, the estimation of tiplocation is updated when the model is updated and thus the matching ofimages to the model may also change. Optionally or alternatively,assumptions on the tooth model (e.g., continuity and smoothness) and/orstylus motions are used to define constraints on the model which areminimized by a global (and/or local) optimization method.

System for Producing Dental Prosthetic

Optionally, embodiments of SGMP can be part of a system for producing afitted dental prosthetic (e.g. crown or bridge). FIG. 12 is a schematicdiagram of an embodiment of a system for producing a fitted dentalprosthetic. A subgingival margin probe (SGMP) 1216 is connected to aremote processing application 1280. As described above, in someembodiments connection is wireless and in some embodiments connection isby cable. In some embodiments remote processing application 1280 isentirely or partially hosted by a machine in proximity to the user (e.g.machine in dentist's office). In some embodiments remote processingapplication 1280 is entirely or partially hosted by a remote server.Communication between SGMP 1216 and remote processing application 1280,in some embodiments, is via standard communications techniques. SGMP1216 collects measurements which can be, for example, optical e.g.images, mechanical, magnetic, and passes the measurements to a toothmodel generation module 1282 within processing application 1280. Toothmodel generation module 1282 generates a model of the tooth from thecollected measurements. In some embodiments the generated tooth modelincludes subgingival regions of the tooth. Tooth model generation module1282 can also access information held in a database 1286. Database 1286can hold previously collected measurements by SGMP and/or previouslygenerated tooth model/s and/or information collected by anothermeasurement device 1288 or devices (e.g. impression, digital impression,CT, MRI, X-ray images). A user, through user interface 1284, can controland/or send instructions to SGMP 1216 and interact with tooth modelgeneration module 1282 and database 1286.

A prosthetic model generation module 1290 constructs a prosthetic model,using information from tooth model generation module 1282 regarding oneor more than one tooth and optionally using user instructions from userinterface 1284 and optionally using information from database 1286. Inone embodiment database 1286 includes a model of the tooth beforepreparation, which was provided by SGMP scanning or another method. Insome embodiments the model of the tooth before preparation is used toconstruct a prosthetic model which matches the patient's original tooth.In some embodiments user interface 1294 is connected to prosthetic modelgeneration module 1290 so that, for example the user can view theprosthetic before sending it for construction. In some embodiments theuser manually indicates a prosthetic finish line: The user, through userinterface 1284, indicates the prosthetic finish line on the generatedtooth model or on the generated prosthetic model.

Optionally SGMP includes processing application 1280 or SGMP includes anadditional processing application. Optionally SGMP includes a userinterface. For example, a SGMP processing application and user interfacecould provide real time feedback regarding measurements and/orgeneration and display of a basic tooth model guiding the user inmeasurement collection, leaving processing application details of modelgeneration to processing application 1280.

Optionally, the user evaluates the quality of the tooth preparation,(e.g., to determine if the margin has a proper shape and/or dimensionsand/or if a crown or bridge will be strong and/or durable enough) byviewing the tooth model through the user interface, optionally decidingto continue preparation (e.g. drilling) and re-scan.

Optionally, the user evaluates the quality of the measurements byvisually checking the tooth model, e.g. through the user interface.

Optionally, the processing application evaluates the quality of themeasurements or the scan, for example by checking that a preparationfinish line is detected (e.g. by evaluating tooth surface slope andfinding a preparation margin step feature). In one embodiment theprocessing application, through the user interface, indicates that aportion or portions/s of the tooth should be rescanned. It should beappreciated that multiple processing models may be provided, forexample, at a dentist office, at a prosthesis manufacture clinic and/orat a remote server. Each such application may provide only some or allof the functionalities described herein, for example, as modules. In anexemplary embodiment of the invention, one or more of the followingmodules are provided: image to model registration module, stylus tiplocating module, image depth extraction module, marking analysis module,self-calibration module, moving stylus tracking module, sensorprocessing module, model combining module, model registering module,image-image combining module, supra-gingival model creating moduleand/or subgingival model creating module. The functionality of one ormore of the modules may be, for example, as described herein.Optionally, the modules are provided in transitory and/or non-transitorystorage (e.g., flash memory and/or mechanical hard disk).

In some embodiments the SGMP and processing application produce a toothmodel which is physically constructed (e.g., by 3D printing and/ormilling) and the physical model is used, as is known in the art oftraditional and/or digital impression, for construction of a prosthetic.

It is noted that, optionally, the sub-gingival model is added to asupra-gingival model, after the supra-gingival model is acquired byscanning (or otherwise imaging) a cast of the patient's tooth.

Exemplary Calibration Details

In an exemplary embodiment of the invention, the SGMP imager iscalibrated to relate a point or feature seen by at least one camera toits 3D location in relation to imager or imager final optical element.Such calibration may use methods known in the art of image calibration.

The calibration may include at least one imager camera “intra” parameter(e.g. focal length, center offset, lens distortion, CMOS pixels scalingand/or skew factors) and “inter” parameters that relates cameras to eachother (e.g., relative position, orientation, rotation and/or, offset),the latter case being relevant to stereophotogrammetry configurationswhether passive or active. In the active case the calibration optionallyincludes at least one pattern projector “intra” parameters (e.g.pattern, focal length, center offset, lens distortion, scaling, skewfactors) and/or “inter” parameters that relates said at least oneprojector to one or more cameras (e.g., relative position, orientation,rotation and/or, offset),

The calibration can be done, for example, at the factory and/or using orby a known target. One example is a standard checkerboard pattern withgiven square size upon a plane: The distinguishable squares' crosspoints are detected and compared between the reference and resultantimage. The reference image can be a theoretical pattern in case of asingle camera calibration or an image acquired by a different camera.

The deviation between the resultant grid vs the reference one may beformulated into a calibration parameters equation system and solved forparameters extraction. Optionally, scaling is also provided by imagingan element (e.g., a stylus marking) of a known scale.

If the SGMP is dropped or suffers other mechanical shock and/or thermalvariations, calibration may be repeated, for example, as the geometricrelationship between camera(s) and/or projector(s) can be changedthereby. Optionally, such calibration is provided with a user interfacefor use by a dentist.

Other Applications

In some embodiments, the above described methods and device are used formeasurement in additional dental procedures, such as 3D scanning ofpreparation for inlays, onlays, and fillings. In some embodiments theabove described methods and device are used to measure implantconnections and implant abutments including one or more of the implantneck, hexagon, and outer surface connected to the abutment. Oncemeasured, a model may be displayed to a user and/or an existing modelupdated. For example, a measurement of nearby teeth may be used to showthe orientation and/or position of an implant relative to other teethand/or a jaw and/or a CT data set.

In some embodiments the methods and device are used to measure sulcus orpocket depth. The sulcus or pocket depth is the distance between thefree gingival line (or gum line) and the sulcus or pocket bottom. Thesulcus depth is a common measure used in evaluating periodontal diseaseor other pathological conditions. Pocket depth can be tracked over timein order to evaluate the effect of a dental treatment. In someembodiments SGMP is used to measure sulcus or pocket depth by applying aconstant insertion force while inserting the stylus into the sulcus orpocket, similar to measurements taken using a periodontal probe. In someembodiments the device measures the applied insertion force (e.g. usingload cell 854 and/or by using force sensor 923) verifying that theapplied insertion force is within a valid range. In some embodimentsdevice and method described in this document are used to measure othercommon dental or periodontal markers, such as Clinical Attachment Level(CAL).

Another use for the device is the marking of areas with certaininterests on the teeth and the gum, such that the dentist can touch orscan features on teeth or in the mouse to mark them on tooth or teethmodel, by a special indication. Such features can be, for example,features that should be marked for other dentists or technicians orusers for further treatment. Some examples include the boundary betweenthe artificial part of the prepared tooth (filling or build-up) and theorganic part of the tooth (Dentine or Enamel), which in many casescannot be seen in the intraoral scanners 3D models.

Another example is marking an area of the new gum line that the dentistwould like to create via surgery. This procedure may be of interest foresthetic reasons to design and demonstrate the result to the patient orother dentists. In this example, the system measures a contact with thegum relative to the tooth peg, but display may be, for example, overlaidon a 3D model showing the tooth with the crown.

Another example is collecting marks and/or data with the device on toothor teeth or mouth cavity model for transfer to a third party, forexample, other attending dentists and technicians and/or oral surgeons,for example, for further treatment and/or consultation.

Optionally, the data collected is presented to the patient to enhancedinformation about the treatment and provide visual explanation of theoutcome of the treatment. This usage may enhance patient approval andacceptance of the treatment and increase patient satisfaction.

Exemplary Implementations

FIG. 16 is a schematic diagram of a side attached angled stylus. FIG. 16shows an exemplary stylus shape where stylus 1618 contacts preparedtooth 1604 at a stylus tilt angle which is not 90°. Stylus 1618 isattached to main body 1620 at the side through housing 1654. SGMP alsoincludes a cover 1674 including a transparent window 1676, a mirror 1656(final optical element).

In some embodiments SGMP includes an adaptor which attaches to animager. In some embodiments the adaptor includes a stylus, a cover, anda connector for attaching the adaptor to the imager. In some embodimentsattachment of the adaptor to the imager is rigid, for example, being asnap or thread attachment. In some embodiments the adaptor connection tothe imager allows the adaptor some freedom of movement causing movementof the stylus with respect to the imager. In some embodiments themovement of the stylus with respect to the imager can be compensated forby optical tracking. In some embodiments the adaptor is used with anexisting intraoral scanner. In some embodiments the adaptor is astandard cover for existing intraoral scanner to which a stylus has beenattached. In some embodiments the imager sits inside the adaptor. Insome embodiments the adaptor is side attached to the imager and includesan angled mirror to provide the imager with views of the stylus, andstylus tip. In an exemplary embodiment of the invention, however, thecover is made rigid enough to avoid unwanted movements of the stylus.

In an exemplary embodiment of the invention, a dentist can purchase aset of covers or covers with integral styluses or styluses (e.g.,depending on the implementation). For example, a kit including 10, 15,40 or 100 (or intermediate or greater numbers) of covers, stylusesand/or integrated covers with styluses may be provided.

In some embodiments, housing 1654 connecting between main body 1620 andstylus 1622 includes a mechanism to measure stylus movements and/ordeflection and estimate tip location, for example, such as describedbefore. In some embodiments housing 1654 connecting between main body1620 and stylus 1622 includes a mechanism to move stylus 1622 andmeasure tip location, for example, such as described before. In someembodiments housing 1654 is connected to electronic unit that providespower and read data from housing 1964. In some embodiments housing 1654provides only mechanical connection between stylus 1622 and main body1620 and stylus tip location is measured through imager, for example, asdescribed before. In some embodiments housing 1654 includes a connector1655 for connecting stylus 1622 to main body 1620 through housing 1654.In some embodiments connector 1655 for connecting stylus 1622 to housing1654 includes a release button 1656 for easy release of stylus 1622. Insome embodiments stylus 1622 is disposable. In some embodiments housing1654 and stylus 1622 are a single disposable unit.

FIG. 17 is a schematic diagram of an adaptor including a mirror sidewhich attaches to an imager. An adaptor 1778 includes a stylus 1718attached to a cover 1774 through housing 1754. In some embodiments,housing 1754 includes actuator/s, and/or sensor/s (e.g., load sensor) asdescribed previously. Cover 1774 includes a mirror 1756, a transparentwindow 1776 over an entrance aperture 1758. Cover 1774 attaches to animager 1730.

FIG. 18 is a schematic diagram of an adaptor which covers a part of animager including an optional mirror, according to an exemplaryembodiment of the invention. As shown, FIG. 18 schematically illustratesa SGMP with a stylus attached to an imager 1820 through an adaptorshaped as a cover 1874. The adaptor includes a stylus 1818, a housing1854, and a cover transparent portion 1876. Imager 1830 includes animager main body 1820, one or more camera 1832 and optionally a mirror1856. Cover 1878 covers a portion of an imager main body 1820. Housing1854 connects stylus 1818 to cover 1874.

In some embodiments stylus 1822 is rigidly connected to cover 1874through housing 1854. Optionally, cover 1874 can be secured rigidly toimager 1820 with mechanical pressure applied by attachment mechanism andcan optionally be released by pressing a release button.

In some embodiments housing 1854 connecting between cover 1874 andstylus 1822 includes a mechanism to measure stylus movements and/ordeflection and estimate tip location, for example, such as describedbefore. In some embodiments housing 1854 connecting between cover 1874and stylus 1822 includes a mechanism to move stylus 1822 and measure tiplocation, for example, such as described before. In some embodimentshousing 1854 is connected by wires (not shown in FIG. 18) to electronicunit that provides power and read data from housing 1854. In someembodiments housing 1854 is connected wirelessly to electronic unit andincludes a power source that provides power to housing 1854. In someembodiments housing 1854 is also electronically connected to imager 1820through an electric contacts between cover 1874 and imager 1820 (notshown in FIG. 18) to provide power and/or read data from housing 1854.In some embodiments, housing 1854 provides only mechanical connectionbetween stylus 1922 and cover 1874 stylus tip location is measuredthrough imager, for example, as described before. In some embodimentshousing 1854 includes a connector for connecting stylus 1822 to cover1874 through housing 1854. In some embodiments stylus 1822 isdisposable. In some embodiments cover 1874 and stylus 1822 are a singledisposable unit.

FIG. 19 is a schematic diagram of a SGMP with a stylus attached toimager 1920 with by adaptor 1930, in accordance with an exemplaryembodiment of the invention. Optionally, stylus 1922 is rigidlyconnected to adaptor 1930. In some embodiments adaptor 1930 can besecured rigidly to imager 1920 with mechanical pressure applied by anattachment mechanism and/or can optionally be released by pressingrelease button 1918. In an exemplary embodiment of the invention, imager1920 includes a window 1958 and may include a mirror 1956, for exampleas shown in FIG. 19, or other optical elements.

In some embodiments housing 1954 connecting between adaptor 1930 andstylus 1922 includes a mechanism to measure stylus movements and/ordeflection and estimate tip location, for example, such as describedbefore. In some embodiments housing 1954 connecting between adaptor 1930and stylus 1922 includes a mechanism to move stylus 1922 and measure tiplocation, for example, such as described before. In some embodimentshousing 1954 is connected by wires (not shown at FIG. 19) to electronicunit that provides power and read data from housing 1954. In someembodiments housing 1954 is connected wirelessly to electronic unit andincludes a power source that provides power to housing 1954. In someembodiments housing 1954 is also electronically connected to imager 1920through an electric contacts between adaptor 1930 and imager 1920 (notshown at FIG. 19) to provide power and/or read data from housing 1954.In some embodiments housing 1954 provides only mechanical connectionbetween stylus 1922 and adaptor 1930 and stylus tip location is measuredthrough imager, for example, as described before. In some embodimentshousing 1954 includes a connector for connecting stylus 1922 to adaptor1930 through housing 1954. In some embodiments stylus 1922 isdisposable. In some embodiments adaptor 1930 and stylus 1922 are asingle disposable unit.

In some embodiments imager 1820 and/or 1920 is an independent 3Dintraoral scanner, for example, a commercially available intraoralscanner. In some embodiments the software of intraoral scanner ismodified to include components for detection of stylus location fromimager and combine it with tooth model. Optionally or alternatively, thesoftware of intraoral scanner is modified to include components forremoving stylus image from images used for creation of the tooth model.In some embodiments the software of intraoral scanner is modified toinclude components that use information from additional sensors forestimating tip location and/or combine that information for obtaining atooth model.

In some embodiments attachment of the cover 1874 and/or adaptor 1930 tothe imager 1820 is rigid. In some embodiments the adaptor connection tothe imager allows the adaptor some freedom of movement allowing movementof the stylus with respect to the imager. In some embodiments themovement of the stylus with respect to the imager is compensated for bymeasurement using optical tracking and correction. In some embodimentsan imager sits inside the adaptor.

As used herein the term “about” refers to ±20%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

The term “consisting of” means “including and limited to”.

The term “consisting essentially of” means that the composition, methodor structure may include additional ingredients, steps and/or parts, butonly if the additional ingredients, steps and/or parts do not materiallyalter the basic and novel characteristics of the claimed composition,method or structure.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

1-29. (canceled)
 30. A device for measuring regions of a toothcomprising: a main body comprising a final optical element of an imagerwhich defines an optical field of view directed in a first direction; anelongate measurement element coupled to said main body and extendinggenerally in said first direction; and circuitry for estimating amovement of said tip relative to said body based on an image acquiredvia said imager; wherein a tip of said measurement element is sized andshaped to be inserted between a tooth and adjacent gingiva; wherein saida distance between said tip and said body is small enough so that saiddevice can fit inside an adult human mouth; and wherein said opticalfield of view is sized to image at least part a tooth when such tooth iscontacted by said tip.
 31. The device of claim 30, wherein said tip isformed of or covered with a material softer than tooth dentin.
 32. Thedevice of claim 30, wherein said elongate measurement element is in theform of a stylus.
 33. The device of claim 32, wherein said stylus isflexible.
 34. The device of claim 30, comprising at least one sensorwhich senses contact of said tip with said tooth.
 35. The device ofclaim 30, comprising at least one sensor which detects a deflection ofsaid elongate element.
 36. The device of claim 30, comprising at leastone sensor which detects a movement of said tip.
 37. The device of claim34, wherein said sensor is located at a coupling between said measuringelement and said body.
 38. The device of claim 34, wherein said sensoris located at or adjacent said tip.
 39. The device of claim 30,comprising an actuator which moves said tip in a scanning pattern. 40.The device of claim 30, wherein said scanning pattern comprises avertical scanning.
 41. The device of claim 30, wherein said opticalfield of view comprises at least two overlapping fields of view.
 42. Thedevice of claim 30, comprising said imager.
 43. The device of claim 30,wherein said final optical element comprises a mirror.
 44. The device ofclaim 30, wherein said elongate measurement element comprises at leastone marking or light source positioned in said field of view.
 45. Thedevice of claim 30, comprising at least one illumination element whichilluminates said tooth and said measurement element.
 46. The device ofclaim 30, comprising a cover on which said elongate measurement elementis mounted.
 47. The device of claim 30, wherein said tip is thicker thana thickness of said elongate measurement element adjacent said tip. 48.The device of claim 30, wherein said tip is rounded.
 49. The device ofclaim 30, comprising circuitry for estimating a location of said tipbased on an image acquired via said imager.
 50. (canceled)
 51. Thedevice of claim 49, comprising circuitry for generating a surface ofsaid tooth, including at least one sub-gingival surface portion usingsaid estimated location.
 52. The device of claim 49, comprisingcircuitry for interpreting a contacting of said tip as an input to marka tooth model with additional information. 53-60. (canceled)
 61. Adevice for measuring regions of a tooth comprising: a main bodycomprising a final optical element of an imager which defines an opticalfield of view directed in a first direction; an elongate measurementelement coupled to said main body and extending generally in said firstdirection; and circuitry for: estimating a location of said tip based onan image acquired via said imager; and generating a surface of saidtooth, including at least one sub-gingival surface portion using saidestimated location; wherein: a tip of said measurement element is sizedand shaped to be inserted between a tooth and adjacent gingiva, said adistance between said tip and said body is small enough so that saiddevice can fit inside an adult human mouth, and said optical field ofview is sized to image at least part a tooth when such tooth iscontacted by said tip.
 62. The device of claim 61, wherein said tip isformed of or covered with a material softer than tooth dentin.
 63. Thedevice of claim 61, wherein said elongate measurement element is in theform of a stylus.
 64. The device of claim 63, wherein said stylus isflexible.
 65. The device of claim 61, comprising at least one sensorwhich senses contact of said tip with said tooth.
 66. The device ofclaim 61, comprising at least one sensor which detects a deflection ofsaid elongate element.
 67. The device of claim 61, comprising at leastone sensor which detects a movement of said tip.
 68. The device of claim65, wherein said sensor is located at a coupling between said measuringelement and said body.
 69. The device of claim 65, wherein said sensoris located at or adjacent said tip.
 70. The device of claim 61,comprising an actuator which moves said tip in a scanning pattern. 71.The device of claim 61, wherein said scanning pattern comprises avertical scanning.
 72. The device of claim 61, wherein said opticalfield of view comprises at least two overlapping fields of view.
 73. Thedevice of claim 61, comprising said imager.
 74. The device of claim 61,wherein said final optical element comprises a mirror.
 75. The device ofclaim 61, wherein said elongate measurement element comprises at leastone marking or light source positioned in said field of view.
 76. Thedevice of claim 61, comprising at least one illumination element whichilluminates said tooth and said measurement element.
 77. The device ofclaim 61, comprising a cover on which said elongate measurement elementis mounted.
 78. The device of claim 61, wherein said tip is thicker thana thickness of said elongate measurement element adjacent said tip. 79.The device of claim 61, wherein said tip is rounded.
 80. The device ofclaim 61, comprising circuitry for estimating a movement of said tiprelative to said body based on an image acquired via said imager. 81.The device of claim 61, comprising circuitry for interpreting acontacting of said tip as an input to mark a tooth model with additionalinformation.